Yahenni, Undying Partisan
Aether Revolt — Rare
Legendary Creature Aetherborn Vampire
Yahenni, Undying Partisan rulings:
2/9/2017 : If Yahenni and a creature an opponent controls die simultaneously (perhaps because they fought or were in combat together), Yahenni wont be on the battlefield as its triggered ability resolves. It cant be saved by the +1/+1 counter that would have been put on it.