Card Errata:XYZ-Dragon Cannon

A clause prohibiting special summoning from the Graveyard was introduced with DP2:

New Card Lore: This card can only be Special Summoned from your Fusion Deck by removing from play the above cards on your side of the field. (You do not use "Polymerization".) By discarding 1 card from your hand, destroy 1 card on your opponent's side of the field.

Old Card Lore: This card can only be Special Summoned from your Fusion Deck by removing from play the above cards on your side of the field. (You do not use "Polymerization".) This card cannot be Special Summoned from the Graveyard. By discarding 1 card from your hand, destroy 1 card on your opponent's side of the field.