Slave of Bolas

Oracle Text

Gain control of target creature. Untap that creature. It gains haste until end of turn. Sacrifice it at the beginning of the next end step.

Card Rulings

5/1/2009 You may target a creature you already control.
5/1/2009 If you don’t control the targeted creature when the “at end of turn” ability resolves, it won’t be sacrificed. If it’s still on the battlefield but under another player’s control, the ability won’t try to have you sacrifice it again at the end of the turn after that.