You can Ritual Summon this card with any "Nekroz" Ritual Spell. Must be Ritual Summoned and not special Summoned by other ways. You can discard this card, then target 1 "Nekroz" card in your GY, except "Nekroz of Unicore"; add it to your hand. You can only use this effect of "Nekroz of Unicore" once per turn. Negate the effects of face-up monsters on the field that were Special Summoned from the Extra Deck.