Magikey Unlocking

When your opponent activates a Spell/Trap Card while you control a "Magikey" Ritual Monster or a "Magikey" monster Special Summoned from the Extra Deck: Negate the activation, and if you do, destroy that card, then you can declare 1 Attribute, and if you do that, for the rest of this turn all face-up monsters your opponent controls become that Attribute. You can only activate 1 "Magikey Unlocking" per turn.