Power Artifact 
Enchantment — Aura
Enchant artifact
Enchanted artifact's activated abilities cost 
less to activate. This effect can't reduce the mana in that cost to less than one mana.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyLEGALvintageLEGALcommanderLEGAL