Pontiff Sulyvahn

Whenever Pontiff Sulyvahn deals combat damage to
a player, gain control of target creature that player controls.

Final Form - If your life total is less than or equal to half of your starting life total, Pontiff Sulyvahn has Flying and "Whenever this creature attacks a player create a token copy of it that's tapped and attacking that player, except the token isn't legendary. Sacrifice that token at the beginning of
the next end step".