Well last night the party took on Tarkilar and barely survived. The Evoker's flaming spheres are what got them out alive (half-orc fighter was held, and no one else could get through Tark's damage reduction.)
So they know they've cleared the dungeon, and they're ready to leave with only four of the wands (one is still in the pit of water with the ooze swarm, two got away when Skaven escaped and cut the gondola rope, and Gutterut has the last one.)
They're going to try to rest first, then escape-- except the dominated fighter is going to be compelled to go to the beach to get his "reward" which will give the Kopru one last chance to dominate another party member. If the Kopru succeeds then it will be fighter and thief vs. cleric and evoker at the last Battle of the Beach. If the Kopru fails I'm tempted to have the fighter remove his armor and "come for a swim" to take him out rather than a straight fighter vs. thief, cleric, and evoker.
And then there's Gutterut, hovering about trying to cause mischief. So-- given that situation, can anyone recommend some devilish mischief for him to wreak?
There's poisoning someone while they're fighting amongst themselves...
The party also plans to use their potion of spider climb for the fighter to carry each of the other party members around the walls and up to the ledge to escape. I think it would be funny for Gutterut to interfere with an encumbered (carrying party member) spider-climbing fighter while he's stuck 50+ feet up on a wall.
If the fighter manages to make a Will save vs. being dominated when he's told to either attack the other party members or go swimming AND the thief makes his Will save vs. dominated + another one for doing something against his nature, then there could be a Kopru fight, but there's no way the Kopru's coming out of the water, and I can't imagine the party going in of their own free will.