Head to the top of Nespirah and slay Overseer Idra'kess.
My men are flagging, <name>. We won't last much longer against these naga, I'm afraid. With the Idra'kess' weapons, and Nespirah's pearls, we should be ready to bust out of here.
Follow the wall to the southeast, and look for a ramp to the upper chamber. I assume their leader is in there, or perhaps the key to Nespirah's awakening. Hopefully both.
If you feel strong enough, head up to the top of the shell and look for some answers.