Text (10): {X}: ~this~ becomes an X/X Construct artifact creature until end of turn.
You can use the ability again to change its power/toughness. For example, if you paid 3 mana earlier to make it 3/3, you could pay 2 to make it 2/2, or 4 to make it 4/4 later in the turn. [Urza's FAQ 1998/10/05]
If Power Artifact is used it can decrease your payment. For example, if you can choose for X=4 and pay just 2 mana to get a 4/4 creature. [D'Angelo 1998/10/08]
It cannot attack until it starts a turn in play under your control. [D'Angelo 1998/11/25] See Rule 302.6.
It didn't get a creature type until Oracle 2007/07/13. [D'Angelo 2007/07/15]
