Kaervek's Purge 
Sorcery
Destroy target creature with mana value X. If that creature dies this way, Kaervek's Purge deals damage equal to the creature's power to the creature's controller.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyLEGALvintageLEGALcommanderLEGAL