Druids' Repository 
Enchantment
Whenever a creature you control attacks, put a charge counter on this enchantment. Remove a charge counter from this enchantment: Add one mana of any color.
Legality
standardNOT LEGALpioneerNOT LEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL