Text (M10): 0/0. ; You may have ~this~ enter the battlefield as a copy of any creature on the battlefield.
Note - Also see Copying Objects, Rule 706. There are enough important rules there that they are worth reading first.
As a copy, the Clone copies all characteristics of the chosen creature. This includes name, color, power/toughness, abilities, and more. [CompRules 2001/07/23] For example, a copy of an artifact creature can be Disenchanted.
Can be used to copy a Vesuvan Doppelganger. You get a Doppelganger and the Clone is mimicking the same creature the Doppelganger was until the next upkeep. It also copies the ability to change forms. See Vesuvan Doppelganger for details. [D'Angelo 2001/08/31]
The Clone is not treated as a Creature - Clone card in addition to the type of its target. [Duelist Magazine #10, Page 43]
Clone is not a targeted creature spell. [D'Angelo 2001/08/15]
If there is nothing to copy or you choose not to copy something, the Clone is 0/0 and will die if nothing prevents that. [D'Angelo 2001/10/31]
Extended tournaments (see Rule 913) banned this card from 1999/10/01 until 2002/11/01.
Note - Prior to Ninth Edition and Oracle 2005/08/01, this card was of creature type Clone and not of type Shapeshifter.