Ketek-Kizu, the Living Armor

Double Strike
Armor 3 (Whenever a creature with Armor 3 would
be dealt damage, prevent 3 of that damage.)
Inviolable (As long as this card is in your hand or
on the battlefield, it cannot be discarded, exiled, or
sacrificed.)
Whenever Ketek-Kizu would die, you may put it
on top of it's owners library instead.