S'hanni, Dragonborn of Destiny

Type is also Khajiit Mage. Whenever a creature you control deals damage to a player, you and that player each gain that much life.

{3},{t} "Feim Sei Gron" / "Become Ethereal": S'hani and 1 target creature gain hexproof, first strike, flying indestructible until your next turn.

At the beginning of your end step, if you have at least 15 life more than your starting life total, each player that this creature attacked this turn loses the game.
(Based on Angel of Destiny.)