Text (SA+errata): If a creature would enter the battlefield under an opponent's control this turn, it enters the battlefield under your control instead. [Oracle 2009/07/08]
This can be played in response to an opponent playing a Creature spell. Since this spell will resolve first, you will gain control of the creature when it enters play. [D'Angelo 2008/10/12]
This affects both token and non-token creatures. It affects creatures that come into play by any means. [Shards of Alara FAQ 2008/09/23]
If there are choices made or actions taken by the creature's controller as the creature comes into play (such as the Devour ability choosing and sacrificing), you get to make those choices and take those actions. Choices made prior to it coming into play are made normally. Look for the text "as ~this~ comes into play" for things that will act differently. [Shards of Alara FAQ 2008/09/23] Some cards that are specifically affected include: Voice of All (you choose the color), Clone (you choose what it copies). [Shards of Alara FAQ 2008/09/23]
It only applies to creatures that come into play while this card is in play. [Shards of Alara FAQ 2008/09/23]
If there is more than one Gather Specimens in play by different players that can be applied at the same time, the controller of the spell or ability that is putting the creature into play decides which order to apply the Gather Specimens effects in. Each one gets only one chance to apply, so the last one applied "wins". In two player games, only one Gather Specimens normally can be applied at any given time so there really isn't a choice in those cases. [Shards of Alara FAQ 2008/09/23]
