During the Main Phase: Fusion Summon 1 Fiend Fusion Monster from your Extra Deck, by banishing materials mentioned on it from your field or GY. If Fusion Summoning a "Dark World" monster this way, you can also discard monsters as material. During your Main Phase, if this card is in your GY: You can add this card to your hand, then discard 1 "Dark World" monster. You can only use each effect of "Dark World Accession" once per turn.
