I'm at the end, Kerghan turns into that monstrosity, this is the ultimate battle...
Or at least it would be, if Kerghan wasn't absolutely useless.
Magnus basically beats him into a bloody pulp with Kryggird's Falchion (Magick sucks though, but it doesn't really matter). Somethimes he realises that he can summon a monster, which is way powerful than him, but most times he only tries to hit us (I don't think he ever managed to do damage, all his hits been dodged), and sometimes he's using some defensive spells. Needless to say, despite it was a somewhat longer battle than usual, I didn't even lose a companion.
Is there a bug with this fight, or is is programmed to be this easy?

It's even easier if you have 20 Charisma and Persuasion mastery. Just sayin'.

(Oh, and those "summoned monsters" are nothing but gore guards. You've seen 'em before.)

Well..it's some time since i played through but i remember it can be very easy but you should take the open world and the open Rulesystem into account, because the difficulty of fights can vay greatly depepending at your level/party/skills and equipment.

That may be the case. RPGs are my worst enemies, since I always try to exhaust them totally. I guess that's why my character became so powerful in the end.

The fight varies largely, though I think the UAP beefs Kerghan up slightly if you don't already have that installed (I could be wrong though). Honestly my own experiences vary massively, usually if I have a large party it's fine but if you try and solo it the fight can be more on the tough side (even with a level 50 character). I find that the biggest problem is when I want some more Arronax related ending slides, as keeping Arronax alive is a pain seeing as he has a non-standard sprite which means you can equip him with little to no armour.

PS If you're looking to have a more interesting ending, slap on Kryggird's Falchion to the Bane of Kree and duke it out - I've still yet to do this but I've heard the ending is quite special.

The fight is like that because Kerghan has 0 in melee skill once he transforms.

Normal monsters gain skill in melee automatically porportionate to their dex stat. NPCs don't. What he turns into is an NPC type, not a monster type (regardless of looks). So he misses like crazy. The game developers couldn't even use their own world editor to solve this, because it's something he transforms into, that is it does not exist in the world map until it happens, so the skill of the dragon form can't be changed by hand.

In some versions, the zombies he summons will attack him instead of you, due to a poorly designed faction conflict. They use the exact same type of monster generator in the Ashbury undead castle to generate Lord's Slave zombies for the Lord of the Damned down there. So, the zombies have to either spawn with the general monster faction , or the friends of Kerghan faction (depending on version), which ultimately determines which master they attack (Kerghan/Lord of Damned).

:) Don't mind it...in openworld/sandbox RPGS i to allways end up like this because i explore everything/try out tso much..that i have a overlevel fast at most games...but..if thinks them to be to easy..we need to kkep in mind..that those storyquest have still to be dooable for a Player "playing a strait line" along the Mainstoryline.

Gotta try that out!
Well, he refused to join me because my character had an alignment so spotless, that even the Avatar would find it suspicious. Fortunately there are character editors available, so I can change this. (also, I jaust started over with a new character, who happens to be ugly, so everyone treats him like crap, and he mostly has to do very illegal stuff to get money. Social commentary maybe?) In quite a lot of the more "sandboxy" rpgs, mosters tend to level up with you. I do find it an unbelivebly cheap solution to use instead of quest or location specific encounter difficulty, but for a final boss, I think I could live with it.