Gothrug, Terror Incarnate

Haste, Trample, Deathtouch
Mana doesn't empty from your mana pools as
steps and phases end.
At the begining of each end step, sacrifice a land
or artifact. If you can't, sacrifice Gothrug, Terror
Incarnate instead. When you do, each opponent
loses life equal to the amount of unspent mana in
your mana pool.
Whenever a Land or artifact leaves the
battlefield, add {b}{r}{g}.