Long-Tailed Black Horse

“If this card is Normal or Special Summoned: You can reveal 1 Zombie monster in your hand and send 1 EARTH Zombie monster from your Deck to the GY; send the revealed monster to the GY, and if you do, this card gains 500 ATK until the end of this turn. You can only use this effect of "Long-Tailed Black Horse" once per turn.”