OMG Nabassu (LOL**SPOILERS**LOL)

[Celacena]

I can't to ulgoth at present as I'm having trouble with installing expansion, but I have completed the TOSC missions a few years ago - anyhow to the point - in BG1, there doesn't seem to be a limit to how many skeletons a cleric can summon - I have had Branwen summon 18 (3x6) regularly, they are really handy to guard the party at night as well as a massive distraction in a fight.
they don't do massive damage - unlike my favourite the skelly warriors, which by BG II I can have 5 of, but couldn't you use them buffed up a bit as an alternative to summoned monsters? in the fight you're talking abut - I'm sure they are better than the kobolds etc that you often get with MS.

as for the better MS - Hobgoblin Elite don't seem that good, but their poisoned arrows can sometimes prove very useful, but I'm getting ahead of myself there.

just a thought that massed undead can pose a health risk to your enemies.

[Andrew Stone]

I haven't played TotSC for a while, but I do remember that particular fight (die, reload, die, reload, die, reload, die, reload...). The tactic that worked for me in the end was to have my 2 tankiest tanks, buffed to the nines, stand toe to toe with His Demoness and try and keep him occupied (many healing potions a must) while the rest of my party, along with as many summoned critters as I could muster up (not that many with Dynaheir unfortunately) took out his stationary guards. I think he took over one of them, but by that time I had dealt with the other guards and just mobbed him. Don't think I've ever quick saved as quickly before or since finally killing him.

Of course, it was only after the quick save that I realised he had cast the death spell on Branwen, who promptly exploded and turned into a ghast. I didn't have the energy to run the whole fight again. Gutted.

[Jordoo]

Potion of mirrir eyes makes you imune to his gaze attack. You can buy some at the inn in Ugloths Beard. Other than that a couple of potions of invisability and your best archer will take out all the cultists. Send him down the stairs invisable. Go to the back of the room and pick them off one at a time they won't attack you. But you must make sure that the one that talks to you and summons Ace Alec doesn't see you. Then take another potion of invisability and go upstairs. Buff your tanks and have them go down by themselfs make sure they drink potion of mirrior eyes. They can attack Ace. Then send the rest of your group to take care off the last cultist.

[wise grimwald]

The last method is basically the same as my first post in August. A variation that can be done with a solo mage is to cast a spell to make him invisible. Take out the cultists with a sling. Because they don't fight back, he doesn't have to be a good shot! Speak to the last one who initiates things, use a potion of invisibility and then one cloudkill spell will kill the beast.
By the way, why use potions of invisibility on a thief when they can hide in the shadows? They are few and far between. I save them for Fighters, Clerics and the like who cannot hide.