The entrance to the Drowned Nations (where the bronze sphere is) is either via the Dead Nations or the Warrens of Thought.

Well the easiest way is to let them capture you - that way you don't need to fight them. You'll just need to complete a few quests or if your charisma is high enough see their boss - then you'll be free to go.

If your evil and you've seen the "boss", you can get the undead to fight each other (and you) - this is much easier than if they all gang up on you.

You can always head to the Warrens of Thought (the entrance is on side of the catacombs opposite of the dead nations entrance), but then you'll have to fight tons of rats (unless you've figured something out, which you cannot do until AFTER you've visited the Dead Nations).

Thanks for the reply. I have been exploring the Warrens of Thought in every corner and killed all those nasty rats but i couldn't find any key to open the door for the Drowned Nations. Probably Wererats holds it but after he imprisoned me i couldn't find him anywhere, i suppose so there is no way out from this situation beside play the game again.

He usually hangs around the entrance I think. You may have killed him and he's dropped his loot in a corner. Have you killed the Many-as-one?

To be honest I normally go through the Dead Nations so I'm not sure exactly how getting into the Drowned Nations via the Warrens of Thought works.

I killed Many As One, at least the rats crawling and composing him on the floor of his throne and they didn't have any special drops. About Mantuok i'm sure i didn't meet him anywhere around after being imprisoned, a bug maybe.

AFAIK Mantouk is supposed to disappear after that meeting with him - where he either imprisons you or sends you to Many As One.

He appears later in the game though, which of course doesn't help with getting into the Drowned Nations.