Volcanic Doomfire (Secret Rare) (SGX1-ENH01) [Speed Duel GX: Duel Academy Box]

Cannot be Normal Summoned/Set. Must first be Special Summoned (from your hand) by sending 1 "Tri-Blaze Accelerator" you control to the GY. During your opponent's Battle Phase, Attack Position monsters your opponent controls must attack this card, if able. When this card destroys a monster by battle and sends it to the GY: Destroy as many monsters your opponent controls as possible, and if you do, inflict 500 damage to your opponent for each monster destroyed by this effect.