Liberator, Urza's Battlethopter
From The Brothers' War set
Liberator, Urza's Battlethopter
Legendary Artifact Creature — Thopter
1/2
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.