Artifact, 4 (4)
Rare
{4}, {T}: An opponent chooses target creature he or she controls. Put a token that's a copy of that creature onto the battlefield. That token gains haste until end of turn. Exile the token at the beginning of the next end step. Activate this ability only any time you could cast a sorcery.
Illus. Donato Giancola

10/4/2004: The token enters the battlefield as the creature it is copying. This triggers its own and any other appropriate enters the battlefield abilities.
4/1/2008: The effect only grants Haste until the end of the current turn. If the creature somehow manages to stick around until a later turn, it will no longer have Haste.
Legal in Vintage (Type 1)
Legal in Legacy (Type 1.5)
Legal in Classic (MTGO)
Legal in Commander