Hakka-Gu, Sly Spark Mage

Commander ninjutsu {u}{r}{w} ({u}{r}{w}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand or the command zone tapped and attacking.)
Whenever Hakka-Gu deals combat damage to a player or planeswalker, you may cast target instant or sorcery spell from your graveyard without paying its mana cost. If you do, shuffle it into your library instead of putting it in a