Osimis

A ghostly figure found in an ancient library deep in xak tsaroth sitting in the golden chair, seemingly engrossed in a book. He is an elderly human in the robes of a scholar. 
How do we retrieve the Disks of Mishakal :
“Down the hall, you will find a waterfall. There are vines that lead downward; it is a difficult climb, so you must be cautious. At the bottom, you will be in a corridor that leads straight to a large hall. Follow that down the steps, and you’ll find the Disks, but you’ll have to fight for them.”
How do we defeat the dragon :
“One of you carries a weapon that can slay the dragon.” He looks squarely at the Prophet (assuming the Prophet is present and possesses the Blue Crystal Staff.)
Where is the dragon’s lair :
“The dragon sleeps in a large circular hall in the ruined city below.”
Where is the secret path to the dragon’s lair :
“You’re assuming there is one. I have heard rumors, but I do not know for certain. Look for its entrance among the Aghar.