[PK]

What I think you're missing is that the meta-enhancement Aura of Power includes the limitation Requires Will Roll (-5%). In other words, by definition, it requires this extra Will roll.

So, first you roll against Will to establish the Aura, because the Requires Will Roll limitation says you have to. Then you roll against Will when your friends enter the Aura, because that's how beneficial Maledictions work.

If that really bugs you, for whatever reason, then just raise the value of Aura of Power by another 5% and BAM! No more initial Will roll required to establish the Aura.

Does that clarify things?