Cavalier of Night 
Creature — Elemental Knight
Lifelink When this creature enters, you may sacrifice another creature. When you do, destroy target creature an opponent controls. When this creature dies, return target creature card with mana value 3 or less from your graveyard to the battlefield.
Legality
standardNOT LEGALpioneerLEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL