Obtain the Ancient Moonstone Seal and bring it to Asterion in Bashal'Aran.
If the grells have come into close contact with the seal that binds my eternal prison, I suspect I know the cause. No doubt the seal has come into the possession of the satyr that lead them.
I feel strongly that this must be true, [player]. One of the satyr must surely possess it. If you can obtain it, you would bring me so close to passing the bars of my prison that tears would come to my eyes.