Liberator, Urza's Battlethopter 
Legendary Artifact Creature — Thopter
Flash Flying You may cast colorless spells and artifact spells as though they had flash. Whenever you cast a spell, if the amount of mana spent to cast that spell is greater than Liberator's power, put a +1/+1 counter on Liberator.
Legality
standardNOT LEGALpioneerLEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL