Mermail Atlanteans were a previously hyped archetype in Gaia Genesis that saw no competitive play due to severe inconsistencies. Since the release of Cybernetic Rebellion, however, the deck went from competitively unplayable to a potential future contender for the Tier List. The box includes a searcher in Mermail Abyssteus, and special summoning capability in Loading... , Loading... , and Loading... . It is important, however, to realize that even though more special summoning has been included, this deck is still considered glass cannon; therefore, playing over-aggressively is not advised. Despite having the potential to be glass cannon, Mermail Atlantean no longer suffering an inevitable lacklustre turn 1 makes the archetype more reliable in competitive play.
Much like the Vampire archetype, Mermail Atlanteans are considered a “toolbox” archetype. Most Mermail monsters have the ability to discard a water monster to activate an effect. Atlanteans compliment these discards because each Atlantean gets an effect themselves when sent to the Graveyard to activate a water monster's effect. As it turns out, Mermail monsters are the ones adding as well as special summoning other monsters, while Atlantean monsters are the ones destroying cards on the field. Moreover, Mermail monsters can only use their effects once per turn, while Atlantean monsters can use their effect more than once in a turn. The main strategy of the deck is to out problematic cards with Atlantean effects so that boss monsters can be summoned without issue.
To get the maximum amount of utility from this guide, it is integral among knowing basic Yu-Gi-Oh mechanics that you also know how to use the toggle button, how to read delays, as well as how chain links work. All of these concepts will be mentioned in the guide.
Since Mermails are complimented well with Atlanteans, the deck does not have a ton of room for tech options. Core cards will be split into Mermails, Atlanteans, Abyss spells and traps, and other useful cards that can help this deck, but are not necessarily integral to the main strategy.
Mermail Abyssteus (2-3x):
Being the main searcher of the deck, it is important to have at least 2 of this card, but 3 is ideal. Having both a discard outlet to special summon and a search effect for a level 4 or lower Mermail helps with tutoring Atlantean destructions and consistency respectively.
Mermail Abyssmegalo (1-2x):
Abyssmegalo is the boss monster of the deck. Being able to search an Abyss spell/trap, as well as having the potential to attack twice in a turn, makes Abyssmegalo scary to deal with. It is more likely that you will summon him off of Loading... or Loading... since 2 water discards leaves you susceptible to a Loading... .
Mermail Abysslinde (2-3x):
Abysslinde is extremely strong, especially in conjunction with Loading... . Having access to any Mermail in the deck when it is destroyed by battle or card effect is extremely relevant.
Mermail Abyssgunde (1-2x):
Your monster reborn of the deck. Abyssgunde is useful for reviving your boss monster Mermails, as well as the smaller Mermails that provide utility.
Mermail Abysspike (1-2x):
Abysspike is the other searcher of the deck. Unlike Abyssteus, Abysspike is limited to adding level 3 waters only.
Atlantean Heavy Infantry (2-3x):
Arguably the best Atlantean, but it is dependent on the format. Being able to out face-up monsters gives the deck notable strength over decks that like to “protect the castle”.
Atlantean Marksman (2-3x):
Marksman is your best Loading... target, while also being a way of destroying set cards. Being able to destroy sets is useful in terms of making pushes for lethal.
Other Mandatory Cards
Deep Sea Diva (2-3x):
Diva is the second strongest Tuner in the game, second to Loading... . On top of being able to summon Synchros, it enables other combos, which will be mentioned below.
Easily the strongest of the Abyss spell and traps. Being able to summon any Mermail from the deck (usually Abysslinde) opens up lots of potential for the deck. Be careful with your use of Sphere if you are running spells since it will not allow you to use them while face-up. Moreover, if you are using this trap during your opponent’s turn, make sure to use it BEFORE their End Phase because if you use it then, you will have to wait until your opponent’s next End Phase. Activate Sphere when it says your opponent is about to end their Main Phase.