This is one of those questions that are hard to answer for a number of reasons. First, we aren’t quite sure how auras work, only that including them in your customs seems to have an empirical effect on those around the user. We’ve tested them extensively and time and time again, the result is the same: auras, whatever they are, are real and you can measure their effect.
That being said, auras are also extremely energy intensive, and customs containing a lot of them can have the side effect of physically draining you. Also, including too many in your custom sometimes causes in a total lack of results, even from the non-aura modules. This seems to be rare, however, with the main side effect of including too many aura modules being physical and/or mental fatigue and a pronounced drop in the efficacy of the aura.
To account for all this, we currently recommend including a maximum of three aura-focused modules, preferably two, in order to make sure your custom works well. By “aura-focused,” we’re referring to modules where the target goal is the projection of an aura to invoke immediate external effects.
This does not include cores that include mild auras as part of their scripting, like Emperor, as the scripting to create those auras are designed to produce much less of an effect, and requires much less energy. Also, aura modules that focuses on changes in body language or vocal intonation should be safe to stack, as these don’t require nearly as much energy.
This DOES include cores where the target goal is solely the projection of an aura, like Love Bomb or Libertine. These cores include energy sourcing and scripting designed to maximize the projection of the aura, meaning they consume A LOT of energy.
If you are attempting to induce a long-term change in your natural aura, split the modules up across two customs, then run them according to the “Getting More Exposure” section in the New Listening Pattern. Do not run them on the same day. Rotate exposure instead.