Obtain a skeleton key from Fendawyr The Half Dragon.
After killing Fendawyr, make your way back to the Up/DownThe Great Shadow Wyrm Draask/Down" class="wikipageedit">? tower on the fifth floor. Prepare for an all CPK area, with only one way out and a death trap. Position yourself just south of the SAFE room, and search to discover a hidden door UP. Unlock this UP using the skeleton key. Head up the spire, following the path until you cannot go UP any further. At the top of the Mighty Spire, there will be a west exit which is a death trap, and a locked east exit. Bash, lockpick or magic unlock this east door and prepare for the encounter with Draask.
Combat with Draask is similar to Fendawyr, but he does hit a great deal harder. Draask will aggro you, so be prepared to calm if you'd like to try to cast dispel magic on him. Flee west if needed.
The fight is generally straight forward and easy, but can hit hard for unprepared players. It can be killed by a skilled hero, and soloed by an archon. Just spell him up and kill him. Like most dragons, he is immune to BASH, and is vulnerable to pierce-type damage.
You sense the following: The great shadow wyrm Draask is immune to bash. The great shadow wyrm Draask is vulnerable to cold. The great shadow wyrm Draask is vulnerable to pierce. The great shadow wyrm Draask is affected by level 300 'sanctuary'. The great shadow wyrm Draask is affected by level 300 'detect illusion'. The great shadow wyrm Draask is affected by level 300 'levitation'. The great shadow wyrm Draask is affected by level 300 'detect invisibility'. The great shadow wyrm Draask has a saving against Magic Orbs, Staves, and Wands modifier of 5. The great shadow wyrm Draask has a Saving against Petrification (i.e., Abjure, Kill, etc.) modifier of 5.
Draask sometimes drops the dragon's hoarde, which is a decent pile of gold.