Azorius Herald 
Creature — Spirit
This creature can't be blocked.
When this creature enters, you gain 4 life.
When this creature enters, sacrifice it unless 
was spent to cast it.
Legality
standardNOT LEGALpioneerNOT LEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL