XYZ-Dragon Cannon [DR1-EN107] Ultra Rare

"X-Head Cannon" + "Y-Dragon Head" +"Z-Metal Tank" This card cannot be Special Summoned except by removing from play the above cards on your side of the field then you can Special Summon this card from your Fusion Deck (You do not use 'Polymerization'). Discard 1 card from your hand to destroy 1 card on your opponent's side of the field.