Oryx, Taken King

Indestructible, Flying, Protection from White, Blue, Red, Green
{2}, {t} : Add {b}{b}{b}{b} to your mana pool.
{b}{b} : Gain control of target creature. That creature gains Decayed.
{b}{b}{b}, {t} : Target opponent loses half their life points rounded down.
If an opponent lost 10 or more life points in a turn, untap Oryx, Taken King at beginning of the end step.