they spawn by script when commander Zhalk gets down to his last few hit points and run into the room from the same door you entered by... this makes it somewhat random as to are you fighting them with your mind sucker pal or if you actually kill commander Zhalk before hitting X health with a big crit the mind sucker will turn against you {and then they spawn} making you have to fight every one and running is your only real chance at that point
I have managed to kill everyone twice [Bard and Cleric of Light runs] by casting "Faerie Fire" on Zhalk giving everyone 10 turns of advanage against him then recasting it against the spawns to cream them before finishing off the sucker with explosion barrels... the timing is tricky and my cleric was lucky because Wisdom was only 14 but i then had time to casually explore the helm
