Here's what I just did:
Upstairs, before going to fight Aec'Letec I had everyone except Dynaheir drink potions of mirrored eyes, because I only had 5. Then I had Faldorn case protection from evil 10' radius on the party. The potions to reject his death gaze, and protection from evil so he cannot target us for that group hold spell he does
Next I went downstairs and used wand of monster summoning once and had Yeslick cast animate dead to distract the demon. I then proceeded to have everyone attack the cultists. Dynaheir got death gazed, so I had to use Yeslick's dispel magic ability on her. This negated the death gaze, but removed my anti death gaze/hold person defense, but I really had no choice as I didn't want to lose any party members. Once my party had slain all the cultists I sicked them on Aec'Letec himself. LUCKILY, my PC cavalier is using the Stupifier, and stunned Aec'Letec, and my party proceeded to pound him into the ground with melee and ranged attacks.
A couple of things. Although it would make the encounter more difficult the cultists should attack you. Maybe they are chanting or performing some ritual, but still they shoulddefend themselves. Also, I don't like cheesing and prepping for a battle before entering the battleground, but I had died against him 10+ times so I said screw it. Also, It seems like Yeslick's innate dispel magic ability removes the death gaze, but the mage spell does not. Is this true?
Anyone else have any methods they'd like to share? Thanks!