Text (WL+errata): 1/1. ; When ~this~ is put into a graveyard from the battlefield, each player sacrifices a creature. [Oracle 2009/07/08]
If another creature goes to the graveyard at the same time as this card, you cannot choose that creature as the one to be sacrificed by the Gatekeeper's triggered ability. This is because you finish putting all the dying creatures into the graveyard before dealing with the Gatekeeper's triggered ability, and therefore those other creatures going to the graveyard with it are not legal targets. [Duelist Magazine #19, Page 34]
The "sacrifice a creature" effect is not targeted. It can affect creatures with protection from black. [D'Angelo 1997/08/27]
Note - This card was creature type "Gatekeeper" until Oracle 2007/05/01, when it changed to "Horror".
