Doombringer

Tapped creatures your opponent(s) control do not
untap unless their controller pays {2}.
{3}: Tap target creature.
{t}, {4}: Tap up to 2 creatures.
It walks along any possible path, wrecking everything
in that path. If something is in that path, it gets rid
of it. It can't be stopped. Even by a mountain. It will
break the mountain itself to make the path
continue.