Having just cleared one of these guys(with repeated bug fixes in LUA, thanks to this topic.
, see
http://te4.org/characters/10195/tome/72 ... 91b24a6f89 for the charsheet.), I think I know roughly where the problem seems to lie.
For me, it would occur, apparently, when I was attempting to attack stealthed or invisible enemies of the type, but not sub-type, I had marked. I'm not 100% sure on this, but it never seemed to happen with the Orc subtype I had marked for...basically the entire time I had Predator, and it didn't just seem to occur against every Humanoid, and it never occured against non-Humanoids that I can recall.
The main reason I'm uncertain of the exact cause is because I wasn't paying attention to what I hit the first time it popped up(so I could have had it pop up against my marked subtype), and in the final battle I don't think either boss is invisible or stealthed, but I had it pop up twice(However, IIRC I got repeatedly blinded in that sequence.).
Still, hopefully that info will help a little.
Edit: Oh, forgot to mention, those it's rather prominent on the sheet; I was using a manaburner weapon for the entire time I had Predator(One of the best weapons I've ever seen, in fact...), except when I tried to take it off for...Gorbat? Wyrmic pride, I always get Grushnak and Gorbat mixed up...and still had the error pop up with it off. I don't think it is related, but it is possible.
