Yu-Gi-Oh! GX Duel Academy Puzzle: 068


 * Exchange the Thunder Dragon in your hand for two copies from your deck.
 * Use The Shallow Grave to return Y-Dragon Head to your field.
 * Normal summon Z-Metal Tank and use X, Y, and Z to Special summon XYZ-Dragon Cannon from your Extra deck in attack position.
 * Use its effect three times to empty your opponent's field, then attack directly.