Great Spell, Collapse of Valhalla
■ [Set] (This card remains on the field.) ■ At the beginning of your main phase, put the top card of your deck into this card's soul. ■ [Act] If there are two or more souls in this card, pay 2 gauge and put this card into your drop zone. If you do, discard all cards from your hand and your opponent's hand, nullify all abilities of monsters on the field, and destroy all cards on the field.