Artifact, 2 (2) Imprint - When Isochron Scepter comes into play, you may remove an instant card with converted mana cost 2 or less in your hand from the game. (The removed card is imprinted on this artifact.) {2}, {T}: You may copy the imprinted instant card. If you do, you may play the copy without paying its mana cost.1
Illus. Mark Harrison
When the activated ability is resolving, you play the copy onto the stack. [Mirrodin FAQ 2003/10/01]
You do not pay the spell's mana cost and any X in that cost is zero. You do still pay any additional costs that might apply, and may pay any optional costs such as Kicker or Buyback that apply. [Mirrodin FAQ 2003/10/01] [WotC Rules Team 2003/10/06]
You can imprint a split card if either side has converted cost 2 or less. After imprinting, you can play either side even if the cost is higher. [WotC Rules Team 2003/10/06]
If the imprinted card is a split card, you can choose which side to play at the time you play the copy. [Mirrodin FAQ 2003/10/01]
You can't play the copy if an effect would prevent it from being played from your hand. [Mirrodin FAQ 2003/10/01]
If this card leaves play while the ability to make a copy is on the stack, the ability will still make a copy using last-known-information rule. [WotC Rules Team 2003/10/06]
If the imprinted card leaves the removed-from-game zone while the ability to make a copy is on the stack, then no copy will be made. [WotC Rules Team 2003/10/06]