Aabad, the Grudgeful

Cannot be Normal Summoned/Set. Must be Special Summoned (from your hand) by shuffling 4 Zombie monsters from your GY into the Main Deck. You can discard 1 Spell, then target 1 monster your opponent controls; send the top card of your Deck to the GY, and if that card is a Zombie monster, that target gains ATK equal to the ATK of the sent monster, until the end of this turn. You can only use this effect of "Aabad, the Grudgeful" once per turn. If this card is destroyed by battle or by an opponent's monster effect and sent to the GY, while the monster that destroyed it is still on the field: Inflict damage to your opponent equal to the ATK of the monster that destroyed this card.