Pugwampi unluck aura

[Unruly]

I'm getting ready to throw a group of Pugwampi gremlins at my party, and I've got a bit of a question about their unluck aura.

The unluck aura says this -

PRD wrote:

A pugwampi radiates an aura of unluck to a radius of 20 feet. Any creature in this area must roll two d20s whenever a situation calls for a d20 roll (such as an attack roll, a skill check, or a saving throw) and must use the lower of the two results generated. This is a mind-affecting effect that does not work on animals, other gremlins, or gnolls. Any character who gains any sort of luck bonus (such as that granted by a luckstone or divine favor) is immune to the pugwampi unluck aura.

What I'm wondering is if the aura stacks, because no mention is made of that in the description. Is it only ever a single extra d20, regardless of how many auras there are, or if you're standing in the middle of 4 unluck auras are you going to be rolling 5 d20's and taking the lowest result? It could even jump all the way up to 16 d20 for a group of 4, since the wording basically amounts to "any d20 roll = 2d20, take the lower," and the second d20 from each unluck aura is still a d20 roll.

I'm assuming, at the very least, that it doesn't stack in the exponential fashion. That would just be way too much dice rolling, and would make it nearly impossible to fight a group of them because you'd almost never hit. But I could see it as having each instance of the unluck aura add an extra d20 to the roll. At the same time I can just as easily see it as being "only 2d20, regardless of how many auras are there."

Is there something, somewhere, that deals with stacking auras that I overlooked? Or maybe I'm just reading too much into the description given. What's everyone here's take on it?

[jjaamm]

only once. would fall under magic. no 2 types of magicwill stack rule.

[Drakkiel]

if the question has anything to do with stacking in most cases the answer is NO...unless specified nothing stacks with something that is the same or similar

[blackbloodtroll]

While it is true that most bonuses don't stack, this is not a bonus.

Whilst this effect provides no numerical subtractions, it is most closely related to a penalty.

Penalties stack.

Pugwampis are possibly the most annoying creatures in the Pathfinder game for this reason.

In Legacy of Fire, they have are responsible for a number near TPKs, for unprepared parties.

[Unruly]

So if it does stack because it's a penalty, in which manner does it stack? Like I said in the OP, I don't figure that it goes up exponentially, but it could easily be read as such due to the wording.

I may have to redesign this particular encounter based on whether or not 4 Pugwampis equals 5 or 16 rerolls, take the lowest. The first is already extremely annoying, and would up the difficulty of the fight considerably, but the second would be excruciatingly frustrating and almost assuredly result in a TPK for the party in question given the situation they're going to be meeting them in. I want the fight to be interesting and hard, not a nearly-guaranteed TPK.

[Drakkiel]

If you are GM then do it however you want to do it...for me...I wouldn't have them stack at all...mostly since rolling that many times for almost EVERYTHING you would slow down combat so much it would drive me insane