Historical Rules · 16 July 2010
Rule 607.2e
Official source text from the 16 July 2010 Rules release
If an object has an ability printed on it that causes a player to pay a cost as it enters the battlefield and an ability printed on it that refers to the cost paid "as [this object] entered the battlefield," these abilities are linked. The second ability refers only to a cost paid as a result of the first ability.