Azorius Herald (C13 6)

Creature — Spirit • Mana cost: {2}{W} • Commander 2013 • Uncommon

This creature can't be blocked.
When this creature enters, you gain 4 life.
When this creature enters, sacrifice it unless {U} was spent to cast it.

"As peace should be—gentle yet unstoppable."
—Augustin IV

Illustrated by Justin Sweet.