Good early noon.

I was playing a Clan Moulder campaign last night that I've since abandoned and was doing Throt's quest battle for the Whip of Domination. There seem several things broken with it, which I don't believe to be due to my mods. I took some screenshots to showcase this.
For one, in the pre-battle screen Ghoritch was...not quite himself. Seems he's changed his name to Morphinrot and enrolled in the Altdorf College of Magic as a Shadow Wizard.
He must love casting spells.

Secondly, during the fly-over cutscene I was already attacked by units which I don't believe is intended. It was Chaos Spawn, I believe.
...And speaking of Chaos Spawn...This is what Ghoritch looked like during the battle. Kill it with fire, please. 

Could you try and see if the same happens for you in-house? Could be due to a mod. Ghoritch worked just fine after the battle on the campaign map afterwards.