Notes & Combos

The Vaylantz field spells synergize extremely well with the Therion cards and skill, acting as a starter, extender, and monster removal. Since activating one of the field spells also activates one from deck on the opponent's field, this counts as "the opponent controlling a card" which lets you use the second skill effect. This was probably not an intentional design choice by Konami but has led to this particular Therion brew unusually powerful and consistent both going first and second.

Activating both skill effects with a Therion name in hand gives you just enough gas to make a going first endboard with Hope Harbinger, Photon Lord, Teardrop the Rikka Queen, Regulus with Fum equipped (negate + bounce), Transmigration and a Therion backrow of choice.

Compared to the Photon Galaxy deck I hit KoG with last month, the one disadvantage this deck has is that it can't cheat out monsters via a skill and has to actually summon them all from the hand via effect. This means it can instantly lose to some targetted floodgates like Tyrant's Tirade and Mind Drain. The going first board also obviously struggles against Sphere Mode and Lava Golem. If the targetted hate becomes popular enough it might be worth using other engines with Therion or simply more spell/trap removal.