"Ominously dark" is a very apt way to describe the interior of the altar place that Vithdovah was guarding, and it was inhabited by horrible creatures not seen elsewhere. Fortunately they were all not very observant, and the shadows played to my strengths being a sneaky type. Especially with the armor that makes me run faster in the dark!
There were hounds that radiated smoke (or just farted a lot).
And a giant winged hound.
And giant shark men? These void gehenoths were often accompanied by scamps (like in Oblivion) or flaming guar (similar to those in Morrowind). As expected they could take a lot of punishment and throw me around with their melee attack.
They also have a creepy smile.
That's why I'd vanish into the shadows, reposition, and backstab (sometimes with slow time) their vulnerable rears, a flaw all the monsters in this place have. These particular ones are also quite slow and easy to get the drop on, meaning it was pretty basic to slay them all with just a little bit of patience.