Cunning 
Enchantment — Aura
Enchant creature Enchanted creature gets +3/+3. When enchanted creature attacks or blocks, sacrifice this Aura at the beginning of the next cleanup step.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyLEGALvintageLEGALcommanderLEGAL