Not to mention that it's mainly due to an incredibly cheap ability that you'll never see again in the series, even when you start fighting similar enemies and worse fairly commonly. *angryface*

I am not in the tower and of course i defeated the horror. If you know how, its actually easy. Well you just need to know how.
So far its not that hard in the tower. But i am just in the 2th lower level and try to solve puzzles.

Oh, you've just been clearing out Durlag's equivalent of tutorial rats on the first level. Fun times ahead. :)

!!!! maybe spoiler!!!!!

Mm.. i think i haven't figured out the ending really. I am again in Ulgoth's Beard and fight the cultist. So far so good. If i am in the cellar and fight the demon after a while my party changes to ghasts. ????? Did i miss something?

That's pretty much the hardest fight in the game. You can leave the room and lure the lesser bad guys to come after you (can't remember what they were but there were some I'm sure) so you can take them out first. Use every buff possible especially magic resistance, bless etc and have plenty of dispels on the ready. Also summon everything you can and send them to the demon guy so he'll attack them instead of your party members. Haste is useful too.

Well it looks like that after awhile a random member of my party to turn in a ghast. First i thought, woo where did he came from but then i realized that it was my ex-party member that attacked my members.
I just don't know how since i did not notice any spell thrown at me.
I will try to leave the cellar but i think they did not follow but i need to try this again. See what happens.
I think i missed that. Thanks for the hint. Now i feel more confident to go in the fight again :)

From gamebanshee: Now I remember better myself - you have to take out the cultists that stand in a circle because if you don't the demon dude will respawn when you kill him. Find every possible potion of magic resistance etc to defend against the death gaze.

The way I managed to deal with him/it was to spawn monsters near him so he was busy with them (a monster wand is great, and keep bringing up new ones as he slays them). Then I went around and dealt with the cultists, which I think was fairly easy as they don't really resist. You're bound to get some people gazed, so have spells or dispelling arrows at the ready. After you fire a dispelling arrow at somebody, just make sure both the recipient and shooter are given new targets, or they can start hitting each other (maybe turning off AI will help here, not sure).

It's an incredibly tough battle, perhaps the toughest in the whole game, so don't feel too bad if you die a lot. Personally I died an awful lot from the entry to that map, because those damn assassins kept backstabbing me and I had no idea of knowing where they were. Keep at it, and hopefully you make it in the end. It's tough as nails!

Drink the potions of protection from petrification OR cast dispel magic. First method preferred and it's easy to see why.

Yeah when you notice some of your characters is "held" -> dispel and pray to god is succeeds :D