Valthalak's soul was stored in this amulet. In our greed we foolishly split it into three parts, not knowing the curse that would await us.
The only way to stop Valthalak's spell is to put the medallion back together. Return to Deliana and tell her that Bodley is her only hope for finding the remaining pieces. Speak to her about any rewards you've arranged for.
I, for once, shall rest in peace. I wish you the best of luck; you shall need every bit of it!