Dahn'myr, the Black Dragon

Immortal (Spells and abilities cannot
reduce this creature's toughness less than 1)
Pay 3 life: Create a tapped 2/2 black zombie
creature token. Activate this only once per turn.
Whenever you have lost 10 or more life from
your starting life total, exil and return Dahn'myr, the Black Dragon transformed.