2008-05-01 : If the ability is activated after the current turn's End step has begun, the tokens won't be exiled until the next turn's End step.

2008-05-01 : The enchanted creature's power is checked at the time the ability resolves. If the enchanted creature has left the battlefield by then, its last known information is used.

2008-05-01 : The tokens will be exiled in the End step even if Elemental Mastery or the enchanted creature has left the battlefield by then.