As you explore Marghor you will come across a grove of trees with only one entrance, and that is blocked by a large stone with a strange symbol on it. Keep going and eventually you'll find another grove of trees, however the single entrance is clear of any obstacles, go in and you will find Shadire, who talks of the Lizard Men and their breeding rooms.

Now head down to level 13, where you will find a prison guarded by Lizard Men and a room of Chickens. Kill them and talk to the prisoner, who will give you the Celestial Symbol, and if you remember the symbol on the rock blocking the entrance into the trees, you will see they are the same. Go back above ground and place the Celestial Symbol on the rock, which will cause it to crumble at your feet, then you will be attacked by 2 red Lizard Men. After you have finished with them, venture further into the grove where you will find the Celestial Sword embedded in stone.

Pull this free and return to level 13, and somewhere down there will be the Incubation Room. Use the switch to one side to lower the spikes, and after you have killed the 2 Lizard Men and the snakes in the room, use the Celestial Sword to destroy the eggs. Now it's time to go above ground once more and talk to Shadire, who will laugh merrily over the Lizard Men's misery, and also give you the Celestial Dagger.

Now all you need to do is make your way down to level 16, where you will come across The Temple of Lizards with 2 pedestals, one containing a crystal which switches sides as you try to retrieve it. Place the Celestial Dagger on the empty pedestal and the crystal will have nowhere to go, so you may now pick up the Crystal of Nobility with ease.