Mariel, Fallen Flight Leader

When Mariel, Fallen Flight Leader enters the battlefield, all opponents must sacrifice 3 creatures. You gain life equal to those creatures converted mana cost. If an opponent cannot sacrifice 3 creatures they sacrifice no creatures and loose 6 life.
Flying, Lifelink, Deathtouch
"Me and my flight once protected this land. Guess whether or not we still do."-Mariel