Enchantment {R}: You may put a creature card from your hand onto the battlefield. That creature gains haste until end of turn. Sacrifice the creature at the beginning of the next end step.1
10/4/2004: You only sacrifice the creature if you still control it at end of turn. If that creature has left the battlefield and come back, you don’t sacrifice it.
5/1/2007: Putting the card onto the battlefield is optional. When the ability resolves, you can choose not to.