Gagagaback (ZTIN-EN004)

During the turn a "Gagaga" monster you control was destroyed by battle and sent to the Graveyard: Special Summon as many monsters from your Graveyard as possible that were destroyed by battle this turn, in face-up Defense Position, then take 600 damage for each monster Special Summoned by this effect. You can only activate 1 "Gagagaback" per turn.