1 WATER monster + 1 DARK monster If this card is Epoch Summoned using a Fiend monster(s) as material: You can place 1 "Abysswalker" Trap directly from your Deck to your Spell & Trap Zone. You can only use this effect of "Abysswalker Nix" once per turn. At the start of the Damage Step, if this card battles a Special Summoned monster: You can make this card's ATK become double its current ATK until the end of the Damage Step. If this card is in your GY: You can send 1 face-up "Abysswalker" Trap you control to the GY; Special Summon this card, but return it to the Extra Deck if it leaves the field. You can only use this effect of "Abysswalker Nix" once per turn.