Gnull, Master Of The Damned

Whenever you cast this creature, return a number
of cratures from your graveyard with a combined
converted mana cost is equal to or less than
1 + the ammount of mana above this creature's
mana cost that you've spent to cast it.
Whenever you cast this creature from any place
other than your hand you may pay any extra
number of {1} to cast it.
"Want to bargain for a soul? I want yours."