Dark Contract with the Swamp King

During your Main Phase: You can Fusion Summon 1 Fiend-Type Fusion Monster from your Extra Deck, using monsters from your hand or your side of the field as Fusion Materials. If you would Fusion Summon a "D/D" Fusion Monster, you can also banish monsters from your Graveyard as Fusion Materials. You can only use this effect of "Dark Contract with the Swamp King" once per turn. Once per turn, during your Standby Phase: Take 1000 damage.