Cainex, The Deathgaze

Firststrike, Deathtouch, Flying
Whenever Cainex, The Deathgaze deals combat damage to a player that player loses life equal to half their life total rounded up.
Whenever Cainex, The Deathgaze attacks defending player may discard three cards to prevent combat damage dealt by Cainex, The Deathgaze this turn.