D:
Have you tried the walkthrough section on the Naga temple on this site? Its under the Forbidden Lands Section.
It's really involved, especially the part on how to get Valdane out of his cell. Getting the gas mask is involved, too-its inside a Level 6 Chest deep within the Naga Temple West. You will probably want to get that before you face the Naga Queen and recover one of the relics of power.
The walkthrough is good and the maps are VERY helpful
James.