Whenever a nontoken creature enters the battlefield under your control, you may pay. If you do, create a token that's a copy of that creature. That token gains haste. Exile it at the beginning of the next end step.
6/22/2015 The token copies exactly what’s printed on the original creature and nothing else (unless that creature is copying something else; see below). It doesn’t copy whether that creature is tapped or untapped, whether it has any counters on it or Auras and Equipment attached to it, or any non-copy effects that have changed its power, toughness, types, color, and so on.
6/22/2015 If the copied creature has in its mana cost, X is 0.
6/22/2015 If the copied creature is copying something else when the ability resolves, then the token enters the battlefield as a copy of whatever that creature is copying.
6/22/2015 Any enters-the-battlefield abilities of the copied creature will trigger when the token enters the battlefield. Any “as [this permanent] enters the battlefield” or “[this permanent] enters the battlefield with” abilities of the copied creature will also work.
6/22/2015 The token is exiled at the beginning of the next end step regardless of who controls it at that time.
6/22/2015 If the ability resolves during a turn’s end step, the token will be exiled at the beginning of the next turn’s end step.
6/22/2015 If the token isn’t exiled at the beginning of the next end step (perhaps because the delayed triggered ability is countered), it remains on the battlefield indefinitely. It continues to have haste.
6/22/2015 If another creature becomes or enters the battlefield as a copy of the token, that creature won’t have haste and it won’t be exiled.