Nel'Vozsh, the Hungering Void

Flying, Deathtouch
Whenever one or more cards you own are exiled
from anywhere, Nel'Vozsh, the Hungering Void
deals damage equal to its power to any target.
If a player would lose unspent mana as steps or
phases end, instead that player loses any unspent
mana and you put a +1/+1 counter on
Nel'Vozsh, the Hungering Void.