Subterrors were introduced to Duel Links on May 20, 2019, and this archetype revolves around "Subterror Behemoth" flip effects, and the recursion of the central card, Subterror Nemesis Warrior, that summons Subterrors from the deck. Despite the inherently slow nature of Flip monsters by themselves, the core trap card, Subterror Final Battle, greatly speeds up the deck and can enable some swift OTKs.
In the past few months, people have experimented with many versions of the deck, with the most popular ones being a pure, Ties of the Brethren, or Trap Monster variant, and some other ones being a Darklord, Thunder Dragon, Invoked, Neos hybrid variant. Out of all of these, the pure variant remains the most consistent, the Ties of the Brethren variant has seen the most tournament success, and the Trap Monster variant can still be seen sometimes on the ladder, while we would recommend either the pure or the Neos versions for the most success on the ladder.
Among the hybrid versions, the Darklord version has the highest power ceiling. The Thunder Dragon variant gives tribute fodder with a plus in hand advantage a few turns later. The Invoked version adds a tiny recurrable engine to just add an alternative line of play that can make use of Behemoths in the GY that were already used. Lastly, the Neos variant adds a layer of protection or aggression (respectively) via sending key cards to the GY with Neos Fusion, as well as a strong body on board that is itself protected from destruction once.
Some potential support cards to look out for in the future for Duel Links are Subterror Guru (a searcher + "Book of Moon" Flip monster to add consistency), The Hidden City (a searcher + disruptor Field Spell to add stability), and Subterror Nemesis Archer (an aggressive nondestructive removal option that is also an answer to Black Rose Dragon). There are other support cards, but for Duel Links, this is all we realistically need.
Also of note, in the Duel Links Meta Discord within the #subterror channel, you can check the Pinned Messages for an FAQ that will be frequently updated, but you can definitely feel free to ask questions there for quick answers as well!
Here are a few example duels showcasing Subterrors in action! NOTE: These don't necessarily show the most recent meta-relevant matchups; the point is to show how the deck works.
Before we proceed, let’s just briefly ask ourselves why people continue to experiment with hybrid builds, among those who continue to use a pure or a Trap Monster build. Keep in mind if you are in the DLM Discord, you are always free to ask members of the channel to help build your deck! Please ask if you want to see builds (especially those not shown in "Sample Decks"), and we will provide.
- The Darklord version adds draw power in the form of Darklord Ixchel (searchable with Banishment of the Darklords), with the ability to plus with Ixchel for synergy with the Labyrinth Builder skill and an added monster effect negate from searching The Sanctified Darklord. It also has good recursion of Ixchel from searching Darklord Contact for follow-up next turn if needed, building a strong persistent board. This is the most expensive version, but highly worth trying if you have the cards.
- The Neos version provides Elemental HERO Brave Neos as a strong body compared to any Flip monster in the game, with a one-time protection from destruction that improves matchups against Ancient Gears, Triamids, and other decks that are able to turn off effect activations or nuke the field with Black Rose Dragon. Provides pseudo-card advantage from a searched Neos Fusion for a later turn when using Labyrinth Builder, which has become more essential to the skill nowadays after the nerf to Masked Tribute.
- The Invoked version uses Aleister the Invoker to give access to Invoked Cocytus (an untargetable helmet-mode attacker) and Invoked Magellanica (a 3000 ATK vanilla), which can be alternative lines of play in scenarios where you don't open enough backrow, or you want in the late-game to make use of Behemoths that were lost in the GY earlier on. A somewhat expensive version, which still plays similarly to the pure version.
- The Thunder Dragon version uses Gold Sarcophagus to instantly provide a Thunder Dragondark as a tribute fodder for Nemesis Warrior by banishing Thunder Dragonroar from the deck, who then returns to the hand for later hand advantage, and then can be used to recover a lost "Thunder Dragon" card. Thunder Dragonhawk floats to mulligan the hand, which is also nice. This is a very fun version if you have the "Thunder Dragon" cards.
- The Ties of the Brethren version adds various Lv 4 EARTH Warriors such as Justice Bringer and D.D. Assailant, to work with Ties of the Brethren in order to flood the field with 3 monsters (including Nemesis Warrior) at the cost of 2000 LP and skipping your Battle Phase on your opening turn. These monsters add one negation of special summoned monsters' effects and a banishing removal option, using the above example Warriors, but most notably, it plusses quite a bit with monsters on the board without relying on using a skill to set that up, leaving you with more backrow to work with, and explains its tournament success. Labyrinth Builder is still a backup skill in a pinch.
- The pure versions are generally more consistent in controlling the field, since they do not require you to carry cards that may be awkward in certain hands, such as Elemental HERO Neos, Darklord Nasten (without Banishment of the Darklords or Darklord Ixchel to go with him), or Thunder Dragonroar AND Thunder Dragonhawk (in the same hand). Flip Flop Frog continues to be a strong Flip monster that is nontargeting nondestructive removal, a fantastic counter to indestructible (by effect) or constantly-reviving monsters such as Invoked Cocytus and Fortune Lady Every, respectively. It also has a good amount of room for tech cards because of not carrying cards from other archetypes.
- The Trap Monster version adds tribute fodder in the form of Trap Monsters like Statue of Anguish Pattern and Tiki Soul, and the former, on the summon of a Trap Monster, can target and destroy any 1 card on the field. Traps are slow though, and sadly, targeting destruction isn't so good nowadays. Once you get set up though, this version makes you play through full backrow and can wear you down with skills like Chain Reaction and Endless Trap Hell.
The following is the best and most-used skill(s) for the deck, but an honorable mention is Draw Sense: Low-Level, which is used in a Trap Monster variant of the deck to draw Nemesis Warrior. There have been a few tops every now and then from users of this skill, but in major tournaments like the MCS or Meta Weekly, and even among just King of Games decks, Labyrinth Builder dominates in usage.
- Labyrinth Builder: This is a similar skill to the now unusable Masked Tribute that people are now flocking to as the next best option.
The main difference is that it shuffles back 2 cards and not just 1, and it is only once per Duel, but at least you could Special Summon whatever you want afterwards, in the same turn, leaving you less susceptible to an interruption before your turn ends. Despite the -1 in card advantage in comparison, it is still worth it over skills like Heavy Starter or Wounded Hero that increase your chances of bricking, or require you to carry bad garnets, respectively.
Heavy Starter: This was experimented with early on after the Masked Tribute nerf, and you might see it on the ladder every now and then to open with the Subterror Behemoths. However, it has been shown to give you hands with multiple monsters and 0-1 backrow card(s) more often than not, which is not so great in a meta where Cosmic Cyclone is incredibly dominant. For casual play or skill farming, this is a good temporary skill, but is not recommended for tournament play.
Reinforcements: This is for the most part only used in Darklord Subterrors (Labyrinth Builder is still used in all the other non-pure versions). Since the deck, with an ordinary hand, can easily pay 2000 LP for the 1800 LP cost of the skill, Nemesis Warrior can be searched right away, with the usual board being Nemesis Warrior, 1-2 Darklord monsters, and 1-2 backrow, one of which is The Sanctified Darklord.
NO LONGER USED:
- Masked Tribute: This skill is pretty much no longer used for this deck at all, because a recent nerf to it prevented Tribute Setting or Special Summoning for a whole turn, leaving the deck susceptible to Treacherous Trap Hole, Sealed Tombs, and Lava Golem, all of which are easily sided for in a tournament setting, even though the former two are not as popular on the ladder right now.
sNTx, KoG October 2019
sevathubie, Anytime Season #17
Gucci, KoG November 2019
These are the cards that are used in almost any Subterror build you may see. Keep in mind that there are other Subterror cards that are not included in this list, that you may want to consider, such as Subterror Behemoth Ultramafus, Subterror Behemoth Stalagmo, and Subterror Cave Clash. However, the below are the most common.
Subterror Behemoth Umastryx (2-3x):
This is your main boss monster, who flips to target and banish your opponent’s monster; that gives this deck a nondestructive removal option, which is very important in the current and future meta, where many monsters have protection from destruction effects. Note that running 2 copies is acceptable, because it is preferred to open with some backrow cards that would protect him, or flip him up on the opponent’s turn as disruption, although a few people do run 3.
Subterror Behemoth Stygokraken (1-2x):
Quite the valuable one-tribute monster. He flips to target and destroy as many face-down cards (on either field) as there are face-up Behemoths you control on flip. He is less useful in the current meta than Umastryx, but he can still be used to help deal with backrow in backrow-heavy decks like Fortune Ladies and Ritual Beasts.
Subterror Nemesis Warrior (3x):
The main recursive option you have in this deck. Perhaps the best part of this monster is his Quick Effect of milling a Behemoth from the deck as cost, then tributing at least 2 monsters (face-up/face-down, including himself, but without targeting) as an effect to Special Summon/Set the milled Behemoth. Not only that, but if you flip one of your Behemoths face-up in any way, you can Special Summon this guy from the GY with priority.
Subterror Final Battle (3x):
This is the best trap card that could have been given for this deck right now. It has multiple uses, most notably, flipping your Subterror monsters (1) face-up or (2) face-down, or (3) bestowing them stats equal to their combined original ATK/DEF for the rest of the turn. The final use, though not often used, is (4) to prevent anyone from negating the effects of Subterror cards that could be activated. Something of note is that it does NOT target the monster that would be flipped or boosted, so you choose on resolution.
Flip Flop Frog (2-3x):
This is a key starter card to this deck. You need monsters that can flip themselves face-down, so that on the off chance you do not open with Subterror Nemesis Warrior, you can still Special Summon Behemoths from your hand. He also provides a disruptive threat on later turns, by being able to bounce your opponent’s monsters back to the hand on flip. Golem Sentry is still also used sometimes, but Flip Flop Frog does not target, and also does not have to Flip Summon, which is extremely valuable.
Deep Sea Diva:
Combined with the Level 5 Labyrinth Wall from the Labyrinth Builder skill, it gives instant access to Crystron Quariongandrax to banish 3 monsters, or Black Rose Dragon to nuke the field. This isn't really used too much in the deck today, but it is a fun option for the ladder sometimes.
This is a very good card for controlling the board, and for making your Subterror Behemoth Stygokraken usable more often. However, as we will see in the matchups below, it can be put to great use against the mirror match to force missed timings.
Statue of Anguish Pattern:
A staple in Trap Monster builds, but isn't otherwise, so it could be considered a tech. When another Trap Monster is summoned alongside it, it pops a card, so it functions in a 2-card combo to be a more aggressive Bad Aim, in a way.
This is a nice option as well, if you are low on copies of Subterror Final Battle, or if you want more ways to flip your Behemoths up on cue. A card that functions similarly in this deck, Ghostrick Scare, is available at one copy and could also be used for more control over which monsters (and how many) are flipped. Recently, this has been dropped for Floodgate Trap Hole or in some cases, Trap Monsters like Statue of Anguish Pattern.
Basically a way to dump Nemesis Warrior in the GY, used in the Neos hybrid variant. Provides a strong body on board as well, with protection from the GY.
Still a very broken card option, and should be considered, since just like Cosmo Brain, Nemesis Warrior can tribute your opponent’s monsters (of any level) if you tribute take them with Enemy Controller.
Some ladder variants occasionally run this to act as some draw power. It doesn't trigger on flip though, only Flip Summon, and doesn't really interact with the opponent. We definitely recommend Flip Flop Frog, or even Golem Sentry, over this (Flip Flop Frog more so).
A pretty decent card in the current meta, if only for the surprise factor. Definitely helps against Ancient Gears' Geartown to make it miss timing, but compared to a few months ago, it is more of a side deck card at this point.
Here's a quick rundown of combos that you can do with this deck. We'll keep it generic here.
Pure Build's Turn 1 SetupSealed Tombs or Lava Golem in the Draw Phase and then summon Subterror Behemoth Umastryx or Subterror Behemoth Stygokraken, depending on the matchup. If Sealed Tombs is on, you would not be able to summon from the deck, and you would not be able to summon Nemesis Warrior from the GY either on flip of the Behemoth.
If Activatable Monster Effects are Turned Off
"Chain Blocking"Red-Eyes Slash Dragon, Dark Cavalry, and I suppose many Counter Traps (which often would negate Nemesis Warrior instead of the Behemoth).
Pushing for OTKSphere Kuriboh or Drowning Mirror Force for example, but should only be done if you are sure that your opponent won't have any more follow-up. Assuming a board state of Final Battle set, with Nemesis Warrior and any other monster (preferably one you can attack with), attack with one or both monsters. Whether your opponent does anything or not, you can chain Nemesis Warrior to that, then tribute Set a Behemoth like Umastryx from the Deck. Flip Final Battle to flip Umastryx, then re-summon Nemesis Warrior. Attack two more times!
Here are the most common matchups in this DARK Monster meta (October-November). Note we will denote any important advantages available in the matchup within pure and any notable hybrid version(s), and that we will be lumping the pure and Trap Monster variants together due to the similarity in playstyle. We'll list the tier 1 decks first and go down from there.
In general, Blackwings function similarly to Koa'ki Meiru in that they can pop cards and swarm the field, but unlike them, they can actually negate monster effects. In this matchup, Cosmic Cyclone will be extremely helpful in stopping them from rolling by banishing Black Whirlwind in chain to Blackwing - Simoon the Poison Wind's Normal Summon effect, or just sniping their Blackbird Close. If they end up opening multiple Black Whirlwind, you should respond with Floodgate Trap Hole to nullify their searches all in one go. They will still get another Normal Summon, but at least you'll stop 2-3 searches.
One of the key advantages that we have compared to other decks is that we don't care about Blackbird Close as long as we go first. They cannot use it as a literal hand trap until they have a "Blackwing" Synchro Monster on the field, but even then, we chain block Blackbird Close because it only works on monsters activating on the field, and Nemesis Warrior activates in the GY, blocking Umastryx from being negated.
That means against their ideal opening play, you can pre-emptively use Nemesis Warrior's effect on the field to tribute Set the Behemoth. Then, Final Battle can be used to flip Umastryx (with Toggle On) to banish the Synchro Monster after they have performed their actual Normal Summon of the turn (after Simoon) if they follow Simoon with e.g. Blackwing - Oroshi the Squall into Assault Blackwing - Raikiri the Rain Shower into their actual Normal Summon. We dodge the counter trap, and then Umastryx's 2700 DEF is enough to wall off Blackwing Tamer - Obsidian Hawk Joe's 2600 ATK, assuming they don't carry a second Raikiri (most builds use 1, which is 2800 ATK under Harpie's Hunting Ground), nor have access to Assault Blackwing - Chidori the Rain Sprinkling (which could get above 3000 ATK easily) right that turn.
Still, it remains that this is a difficult matchup, just because of the deck's ability to basically Normal Summon twice, and because of its access to Hey, Trunade!. One final note is that the deck could side deck Ancient Fairy Dragon to search Necrovalley on their first turn, which instantly turns off Nemesis Warrior's on-field effect...
Pure: Tough matchup, just because of their swarming capability.
Hybrid: Most notably, the Darklord hybrid version can negate their negate as an additional layer of protection, and you'll have more bodies on board to block their attacks. The Ties of the Brethren version has Justice Bringer to negate 1 Darklord monster's effect (but can itself be negated). Otherwise, nothing else stands out about other hybrids in this matchup.
Not surprisingly, one of the most difficult matchups. The current meta is shaped around Darklords, and even after their recent nerf, it is easy for them to search their cards each and every turn by abusing KaibaCorp Bling to draw a glossy or prismatic Banishment of the Darklords that they shuffle into the Deck by the time their turn rolls around, along with their ability to negate monster effects with The Sanctified Darklord. However, Subterrors do have an answer to their negations, so all is not lost. The 4th effect of Subterror Final Battle, previously deemed niche, is currently relevant, because it prevents the effect of The Sanctified Darklord from being able to negate your "Subterror" monsters' effects. They can still gain LP, and the effect will appear to be negated, but your monster will not be affected, as long as you chain to the negation itself, or do it pre-emptively before they can attempt the negation.
As for key points of interaction, if they Tribute Summon Darklord Morningstar, assuming you have Final Battle, your best bet is to tribute Set your Umastryx from the deck. If you no longer control any face-up Effect monsters, Morningstar won't be able to summon anyone else from the Deck. If they Tribute Summon Darklord Desire, the safest play is to use Floodgate Trap Hole to flip it face-down, so that you could save Final Battle to flip Umastryx to banish someone else if needed. The only rough interaction is if they topdeck Cosmic Cyclone to banish your backrow, which can happen because they want to trigger KaibaCorp Bling and they want an out to Necrovalley. Luckily, they can no longer use Hey, Trunade!.
Another hard matchup, mainly due to their access to a turn 3-4+ Black Rose Dragon if you don't take care of their Scrap Goblin as soon as possible. Luckily, Umastryx can just banish it or Stygokraken can just pop it face-down. The most infuriating aspect of this matchup is just that they often carry 2-3 Cosmic Cyclone, which is only to trigger their Sorcery Conduit skill, but happens to be detrimental to a deck like this that has 1-2 backrow in a good hand. They can get lucky and hit your Subterror Final Battle, which is your best out to this deck. They carry Concentrating Current as well, which gives them a boost to absurd ATK amounts, each above the 4700 DEF of Umastryx, plus they'll also have Aleister the Invoker in the hand to boost further. That is the only other scary part about this deck, as it is otherwise slow.
To deal with this deck, Subterror Final Battle is instrumental in just boosting Umastryx to 4700 ATK, forcing them to boost Invoked Cocytus with Aleister 3 times just to survive if you are attacking into them, since Concentrating Current only boosts ATK, which is only relevant when they are attacking you since they are in Defense mode. Invoked Magellanica and Invoked Purgatrio are not huge problems because they can be targeted by card effects. Purgatrio is worth noting though because it can attack all monsters you have.
Overall, Floodgate Trap Hole is your best friend here, alongside Subterror Final Battle to give huge boosts to your Behemoths, and to trigger Umastryx to banish non-Cocytus Invoked fusion monsters (or Scrap Goblin). Set multiple backrow if possible to help them miss your Final Battle with Cosmic Cyclone.
Kind of a weird matchup, not unlike Crystrons and Magnets (see below in "Miscellaneous") since the "Ritual Beast Ulti-" fusion monsters can tag out as a quick effect. If you go first, you'll want to watch them closely to keep track of who they have already Special Summoned. It is best to catch them off guard by using Umastryx to banish the Spiritual Beast Cannahawk right away, so that they cannot set up their banish pile with more than one different kind of monster (Spiritual Beast vs. Ritual Beast Tamer) while also having a fusion monster on the field to tag out for those monsters.
Their typical backrow is Ritual Beast Ambush, which is only usable when they have the aforementioned two different types of Ritual Beasts in the GY or banish piles, Cosmic Cyclone (which again hurts backrow decks as usual), and possibly Floodgate Trap Hole (which we don't care about). Their boss monster is actually Destiny HERO - Plasma, but we don't really care too much because Subterror Final Battle can just be chained to Nemesis Warrior's effect to flip himself face-down, dodging Plasma's Skill Drain effect while still resolving the Special Summon from the Deck. But for real, just Floodgate the Plasma, flip it face-down so you don't have to worry about it. It takes so many resources to get him on the field that you can deal with it.
Overall, not as bad of a matchup as it seems at first. You're going to have to pay attention and have your toggle on though, to watch for key points of interruption which is generally while they do NOT have the Ulti- fusion monsters on the field. Do keep in mind that they do not care about Floodgate Trap Hole because they can contact fuse face-down and the fusion monsters can dodge Floodgate by tagging out on Chain Link 2.
This matchup is actually kind of similar to Desperado (see below) because Fortune Lady Every only banishes face-up monsters, and we can flip face-down. The only crucial thing to watch out for is, don't get too complacent when you see a Lv3 Tuner plus a Lv4 non-Tuner, because they CAN use Black Rose Dragon. If they have Fortune Vision active and they banish Fortune Lady Light in an ideal combo, they can nuke the field without destroying their monsters. Otherwise, Fortune Ladies are backrow heavy, and we deal with backrow with Stygokraken popping face-down cards, and with Every (or any of the other Synchro monsters in their arsenal) with Umastryx banishing them. Lastly, I suppose since they have Enemy Controller, be careful to check that they have NO delays before using Nemesis Warrior's effect (or use his effect before their backrow becomes live), so that they cannot use Enemy Controller to take your non-Nemesis Warrior and fizzle your Special Summon.
Overall, not too much more difficult than any generic backrow deck. Just remember that Every can only banish face-up monsters. Keep yourself face-down until you're ready to react, and don't let them get a Black Rose Dragon, which they will telegraph by having Fortune Vision on the field most of the time (if they aren't dumb, and they actually nuke the field only when they have a follow-up play).
Pure: This is tough to get going against because they prevent you from using monster effects, rather than negating them after they activate, so the pure version has no inherent out if you go second.
Hybrid: Of note, the Darklord version has The Sanctified Darklord which can negate Amano-Iwato, which lets you use monster effects that turn so you can deal with Amano ASAP.
This is a pretty annoying matchup, but then again, it is for any deck that carries Effect Monsters (i.e. most decks). The problem with Amano-Iwato is that it prevents activation of monster effects in the first place, rather than negating them. So, you'll have to just try to snipe their backrow with Cosmic Cyclone, and try to beat over Amano-Iwato with Final Battle on your monsters. Then you'll be free to activate monster effects, which is where things finally get interactive.
If Nemesis Warrior is in the GY and a Behemoth is on the field, you can chain block their counter traps from negating Umastryx (see Combo section for chain blocking notes). Of note, Rebirth of Parshath would still shuffle Nemesis Warrior from the GY back into the deck, which kind of sucks, but at that point there is a good chance you can just kill them that turn with Umastryx anyway. None of the other counter traps that negate monsters do anything because they destroy. Lastly, something to watch out for is that Amano-Iwato decks do sometimes use Concentrating Current, and Amano goes up to 3100 ATK vs. Nemesis Warrior's 3000 ATK after Final Battle, so be careful there, and if they do carry Aleister the Invoker, which some do, they'll also have Magellanica for you to get rid of with Umastryx.
And now, the matchups which are generally considered rogue, but that you shouldn't be surprised to see on the ladder nowadays.
This is a fairly coin-flippy matchup. Whoever opens Subterror Final Battle and also goes first, usually wins, as they are likely to be able to flip up a Behemoth to disrupt your field before you can flip up your backrow. Siding Bad Aim is recommended, as typically you can (1) respond to Behemoths in the hand to pop a monster on their field, disrupting them as they come in or (2) pop the monster that could be tributed, in response to the activation of Nemesis Warrior’s Quick Effect.
Another useful interaction is that Paleozoic Canadia can be chained to your opponent’s starter monsters, like Golem Sentry or Flip Flop Frog, to flip them face-down on Chain Link 2. To do that, chain to the effect they use to flip themselves face-down. That will make the Behemoths miss timing, and often end their turn outright aside from some set backrow.
Lastly, note that you can actually use Subterror Final Battle to flip your opponent's Subterrors face-down in a pinch, either to stop an attack or to act as a pseudo-Canadia for forcing missed timing.
Hybrid: Elemental HERO Brave Neos can strengthen the turn 1 play vs. a Dual Wield + Shi En board, compared to trying to swarm the board with Flip monsters. The Darklord version adds The Sanctified Darklord to negate Shi En. The Ties of the Brethren version lets you use Justice Bringer to negate Shi En's negate. The Invoked version has access to Invoked Cocytus which can't be targeted by anything, and is nearly impossible for conventional Six Samurai decks to beat.
Despite their two nerfs in a semi-limited Shien's Dojo and Legendary Six Samurai - Enishi, they are still a pretty good deck, with consistent draw power in Six Samurai United, a good negation in Legendary Six Samurai - Shi En, and the good nondestructive removal option in Enishi.
To handle this matchup, assuming you are going first, Subterror Final Battle disrupts them by banishing a summoned Fuma with Umastryx to prevent Shi En from coming out. Cosmic Cyclone as a side deck card might also help to banish their typically-one copy of Shien's Dojo, or their Six Samurai United to capitalize on a brick. The nice thing is that going first, the Neos hybrid build provides a turn 1 play that does not require you to put more than 1 card on the field, playing around that Dual Wield.
If you are going second, assuming they have Dual Wield against your pure build, the best play is to simply hope you opened Subterror Behemoth Stygokraken, then tribute Set it using Labyrinth Builder until you are able to take out the Six Style - Dual Wield. Pay close attention to their playstyle though, as they might telegraph a huge brick, in which case you might just be able to bait out the Dual Wield early anyway and still survive. Kind of depends.
Finally, something to keep in mind is that Final Battle does not prevent Shi En from negating another copy of Final Battle. Shi En negates the activation, not the effect, so his negation will go through regardless.
This is kind of a coin-flippy matchup as well. Their best hands can beat over your good hands, but their decent hands can include face-down monsters you don’t necessarily want to pop with Subterror Behemoth Stygokraken. The Neos hybrid build helps put up a stronger wall in comparison.
Since Blue-Eyes often carries cards like The White Stone of Ancients and Dawn Knight, which mill the deck to ultimately summon a Blue-Eyes monster from the deck (most notably, Dragon Spirit of White), it is not a good idea to use Subterror Behemoth Stygokraken to pop them while they are Set. Instead, it is recommended to take it slowly, waiting for a Subterror Behemoth Umastryx to banish it instead.
It is tough to counter Dragon Spirit of White if you detect a delay while you have a monster, because they can chain to your Umastryx to summon Blue-Eyes White Dragon from the hand. Snipe Hunter is also an annoyance that you just want to flip down immediately with Paleozoic Canadia and hope they don't have a follow-up in the form of Cosmo Brain.
If you can handle those two interactions, Blue-Eyes is otherwise a battle-heavy deck, which means if you can consume their resources with Umastryx and Subterror Nemesis Warrior early on, you should be able to take control.
Pure: This is one of the hardest matchups, because their best hand can rip apart your worst hand. If both of you have good hands, you may still be likely to lose your Subterror Final Battle to Ancient Gear Reactor Dragon.
Hybrid: Elemental HERO Brave Neos does help wall off Reactor Dragon with its one-time protection from Neos Fusion as a continuous effect, compared to a more-likely board wipe in the pure variant. The Darklord version can negate Reactor Dragon so that you can use Subterror monster and trap effects whenever you want, and not be afraid of losing backrow.
The main problem in the pure variant against Ancient Gears is that their Ancient Gear Wyvern and Ancient Gear Reactor Dragon turn off monster effects during their attacks, making you flip Subterror Final Battle early to boost your face-up monster, or to banish their monster before they can attack. As such, if you don’t draw Final Battle in time, they will have no problem attacking you. The Neos hybrid variant helps put a strong body to wall off the Reactor Dragon and Wyvern.
Bad Aim is invaluable in this matchup, as it can respond to cards like Double Cyclone or Galaxy Cyclone (including Galaxy Cyclone from the GY) to pop Geartown on Chain Link 2, making it miss timing. It could also respond to the activation of Ancient Gear Fortress to pop an Ancient Gear Castle, if you are detecting a brick and a reliance on Tribute Summoning via Geartown. Cosmic Cyclone is risky, but also nice if you can banish the Geartown or a suspected Drowning Mirror Force.
Lastly, if you are running into a lot of Ancient Gears, Desert Sunlight or Ghostrick Scare are also nice options to have in addition to Final Battle in the pure build, flipping your Behemoths at will.
Perhaps a frustrating matchup if you are a new player. They often interact with you on YOUR turn, so they could dodge your targeting cards. They also can "float" when destroyed (namely, Crystron Ametrix summons a monster from the GY, Crystron Sulfefnir summons into a monster from the deck, and the Tuners Crystron Citree, Crystron Rion, and Crystron Quan dodge targeting effects to go into a Synchro Monster). Always check their GY and banish pile to see what kind of options they have for their Tuners (typically, Ametrix for Level 5 and Powered Inzektron for Level 6; most other Synchros that they make must be on their turn). Keep in mind that they also cannot respond except in your Main Phase and Battle Phase, so you can catch them in the Draw Phase or Standby Phase.
Against them, it's most favorable to go first and flip the Tuner face-down on their End Phase using Paleozoic Canadia, so you can be free to get rid of them on your turn. Also, a big-brain play is to chain Canadia to their effect that could Synchro Summon on your turn, flipping the Tuner face-down to fizzle the Synchro Summon. Something else you can do in addition to maindecking Canadia is to side deck Bad Aim, so that if they use Crystron Rosenix (or Crystron Prasiortle / Crystron Smiger) for example to target another face-up card, hit that card they target with Bad Aim so that they cannot summon a Tuner (they must destroy it using their effect to summon a Tuner). Also, worth noting that we have an inherent counter to their recent support card, Crystron Impact, because Nemesis Warrior chain blocks Umastryx or Stygokraken from being negated (see Combo section)!
If you go second, just play it out as if you are going first, because they take a while to get going anyway. It's rare and resource-intensive to see them going for a Crystron Quariongandrax on Turn 2 or Turn 3. The main things to keep in mind are to respond to their actions and not the other way around, and to be keen to disrupting them in the Draw Phase, Standby Phase, or End Phase.
This deck easily counters DARK Machine decks that utilize Desperado Barrel Dragon, given that Subterrors focus on controlling the board while being able to flip your own monsters face-down, but Desperado loves to destroy face-up monsters. The omnipresent BM-4 Blast Spider also requires a face-up target to destroy so it can turbo out Desperado, so that's another way to just end their turn. Yet another benefit for Subterrors is that Subterror Behemoth Stygokraken can pop monsters that you've flipped face-down using Paleozoic Canadia or Floodgate Trap Hole, which does NOT allow Desperado to even come out.
Despite all that, just watch out for Desperado anyway, because some variants of the deck have absurd draw power from the two (potentially-guaranteed) Cup of Ace, and all variants have full access to semi-limited cards, Cosmic Cyclone, and sometimes the Cyberdark Edge/Cannon engine. (Because Cyberdarks often use Desperado nowadays anyway, this matchup also pertains to Cyberdarks.) Yes, even though Master of Destiny is nearly unusable right now with the recent October 2019 skill nerf, some people ARE still using this deck.
This matchup can be difficult, especially if you are going second (but I suppose it's like that no matter what deck you are playing against them). Their Spellbook of Fate banishes anything without targeting, which is instantly oppressive. However, the numerous hits on the Forbidden/Limited List makes the deck run low on resources fairly quickly in comparison to their full-power days.
The main concern is not really on being able to break their board, but being able to build yours when you go second, because they can just banish your Starter Card and then you can only set 1 or 2 backrow that they can easily deal with later. Silent Magician also negates 1 Spell per turn, but Subterrors tend to run a lot of traps anyway, so it's generally fine.
Going first, this is quite an easy matchup if you can bring in multiple monsters right away. Spellbook players tend to struggle when they can't clear a field of monsters with their 1 Spellbook of Fate per turn and their 1 big Silent Magician, because the deck is made for dealing with backrow and a fairly-sparse monster field, and lost its access to Treacherous Trap Hole quite a while ago. If you want to stop a Spellbook player from playing, use Umastryx to banish their Spellbook Magician of Prophecy (or whatever Spellcaster they use, like Aleister the Invoker or Breaker the Magical Warrior) as soon as it's summoned, so they can't use Spellbook of the Master to start filling their GY. Lastly, a risky thing you could try is Cosmic Cyclone to banish Spellbook of Secrets so that if they don't carry Spellbook Library of the Crescent, they cannot make any more plays that turn (which all stem from Spellbook of the Master). It's risky because they can still likely do something next turn, so if you don't beat them in your turn, they can follow up.
Triamids are kind of like Ancient Gears in a way, but this is a better matchup than Ancient Gears would be. Most notably, Triamids have Triamid Kingolem, which during battle with a Triamid monster, turns off activatable card and effects, just like an Armades, Keeper of Boundaries, but at least it's not a mechanic built into the monsters themselves. Both decks need 1-2 turns to set up an appreciable board (unless Triamids open Treacherous Trap Hole, but that's the case with any new-ish deck).
The key to beating Triamids is to interact on the Triamid player's turn. Using Paleozoic Canadia to flip Triamid Hunter down would slow down their swarming. Flipping Subterror Final Battle to use Umastryx to banish a monster would reduce how many times they can swap out their Field Spell on your turn, or to use Stygokraken to pop their Triamid Pulse in their End Phase prevents them from saving it by flipping it up early on your turn.
If you go second though, a good way to break their board is to tech in Cosmic Cyclone to hopefully snipe their Triamid Pulse (try not to target their Field Spells since they can chain), as their backrow is their main outlet of destruction (you don't want to hit Treacherous Trap Hole, because it's obviously going to be usable immediately and if they carry two, you've let them use both). Perhaps a safer play is to just snipe the already-face-up Pulse in chain to when they use its face-up effect, to "MST negate" it, as it must remain face-up on the field to resolve.
Either way, be sure to win as fast as possible, because Triamid Dancer can boost them by 500 ATK each turn. They start out peaking at roughly 2300 ATK, which is beatable against your 2600 DEF Stygokraken, so don't let them get too big and then attack under Kingolem!
Magnets are kind of similar to Crystrons in a way, because they can dodge your targeting effects on YOUR turn. What's really painful is if they open That Grass Looks Greener and mill really well, because it gives plenty of GY banish fodder for Berserkion the Electromagna Warrior, their main boss monster who can destroy an entire field. They also have Block Dragon, but that's not really relevant because of its ATK being under 2600, and its protection against destruction of face-up monsters by card effects doesn't matter to your Stygokraken and Umastryx. Thankfully, only the little guys have Quick Effects, but this matchup can be a blowout depending on their hand...
As usual, if you go first, you're at an advantage when you can just summon out Subterror Behemoth Umastryx from the deck and banish their monsters. If they've already milled Magnet Conversion, know that they can recover a banished Lv4 magnet easily, so be patient and wait for a Berserkion to come out. Ideally, you want to hit it with a Canadia to be safe, and then by the End Phase, if they haven't followed up with a second one, banish that first one. Magnet Conversion recovering Beta The Electromagnet Warrior could maybe allow them to summon 2 Berserkion in one turn, so keep that in mind. New support gave them Magnetic Field as well, so they could bounce your Behemoth back to the hand I suppose, but they will get hit by its effect beforehand, so it may not be a good idea to attack into you in that case!
If you go second, the best way to deal with them is to attack them and force them to chain and summon Delta The Magnet Warrior, which cannot really do anything other than attack or be destroyed. Therefore, it can clog their field, making it hard for Berserkion to even come out, making them choose between Block Dragon and Berserkion. Even if Berserkion does come out, if it's destroyed, it won't float unless their entire field is empty when Berserkion is destroyed.
Both pure and Neos variants of Subterrors have shown to be extremely viable, as they have topped in some of the past DLM tournaments, and have also performed well in, e.g. DLE at a 50/50 split of the total tops between pure Subterrors and Neos Subterrors. It is on you to test both variants and see which one fits your play style more, as both are extremely viable in the current metagame.
Overall, this is actually one of my all-time favorite archetypes to come to Duel Links, and despite being based around Flip monsters, do not underestimate them. They can easily OTK if given the opportunity, and are quite resilient! Hopefully we will get more support for them in the near future! Hidden City would add amazing consistency support without too much oppression, and Nemesis Archer would be great against a Black Rose Dragon field nuke.
If you made it this far, thank you for reading this guide, and if you have any questions, feel free to ask me about substitute tech cards, any tips and tricks you want to know, evaluation of your replays, etc. I am also open to updating this guide if there is anything you want to add, or if I have made any silly errors! Have fun flip flopping around and watching your opponent squirm! :D