Supreme King's Castle (LDS3-EN036) - Legendary Duelists: Season 3 1st Edition

You can Fusion Summon Fusion Monsters that must be Special Summoned with "Dark Fusion", with effects other than "Dark Fusion". Once per turn, during damage calculation, if your Fiend monster battles an opponent's monster: You can send 1 "Evil HERO" monster from your Deck or Extra Deck to the GY; your monster gains ATK equal to the Level of the monster sent to the GY x 200, until the end of this turn (even if this card leaves the field).