Yeah same for me. First of all it took me about a week straight to get a group. And then another week to find a group who could complete it. Finally we finished it.
What we did was:

Keep 2 people near the king. 1 to heal him and 1 to draw the fire away from him.

Then we Split the rest of the party by placing them in the stairways.
With this strategy the mursaats and jades just came to us.

Covering each direction as they came up

Utilizing nukers and healers and we counldn't be stopped.

And with a good team you can do this mission relatively easy. Its just a really long mission. The hard part is finding a team there that isn't looking for a Healer. I sat around for days until i found a group that needed a nuker