You're really supposed to go here to recover the amulet of kings, though that's not something you'll be able to do.

Your map shows the location of these caverns now, unfortunately no fast travel is possible. Rather travel to cheydinhal and then it's just a small treck upwards.

Once inside, the first gatekeeper speeks to you as a brother. He assumed you're part of the guild and offers to take you tino the shrine. The downside to this however, and the reason why I reloaded a save game after my initial response, is because you permanently loose any gold you carry at that moment.

The second gatekeeper confiscates your stuff, so if you're not smart there you'll find yourself in hostile territory with no ways to defend yourself. If you choose the sneak approach, drop everything before speaking to him.

Alternatively, kill both gatekeepers and fight your way inside. Once inside the antechamber room, go to the right, untill you see a door on the left, that one leads to the actual shrine. The rest here is nice for loot, though comes with the price of having to fight additional guards.

Inside the shrine, regardless of the way you choose to get there, you'll get to listen to a speech from, and for the first time see, Mancar Camoran. If you choose the undercover method, after his speech you're asked to kill a victim lying on the altar there, do so and you cna get out easier, if you don't but instead grab the book mysterium Xarxes (the original) everyone will come at you.

Of course choosing the combat method at first will give you a fight no matter what. Anyway you do it, make sure to grab the book and return to cloud ruler temple.

Getting out of the shrine there is a bit harder as you'll obviously be attacked by just about everyone and their cousin, and you can't exit the same way you came in. From the alter, you came in on the left side but now your exit must be on the right side. This exit takes you to the living quarters in the caverns there.

Head right at the first turn, then left and then take the right turn again. The left is a dead end so if you're being chased, that's the wrong way to go! This brings you to another large room, the exit is to the far left. follow the path again in the next room take the exit on the right, and then turn right again, the door on the left there is not the way so be sure to take the right. The next door you come to brings you back to the very first entrance room at Lake Arrius. And is the way to freedom.

Once outside, travel to Cloud ruler temple and report your success to Martin to finish the quest.