The Zassacre Zirl 
Legendary Creature — Human Assassin
When The Zassacre Zirl enters the battlefield, if you cast them, destroy target commander an opponent controls. If its owner has two or more commanders, that card stops being a commander. Whenever another Commander dies, draw a card.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyNOT LEGALvintageNOT LEGALcommanderNOT LEGAL