Invisibility Sphere needs to affect party only, or is this intentionally left as "make everyone, including neutrals and (if it's unchanged from the first time i saw it years ago) hostiles, invisible"? kinda fun but that's not the point.
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k, the current (and probably original) PRO is INAREASM which is, among very few things, also used with Repulse Undead. you want INAREAPA, instead.