Spoilers . . . . . . . . . . . . You can defend yourself from his attacks with: Protection from Magic Scroll Spell Imunity:Abjuration Protection from Undead Scrolls Weapons that effect him: +4 or better weapons (+4 staff or Rynn sold in adventurers mart) Melf Minute Meteors Ring of the Ram Expiremen...
At the top of the screen there are two star like designs above the map. In the middle of the stars are to circles. One of the circles toggles the map indicators on and off. Not a bug you probably accidently did it. The first time I did it I was freaking out as well.
In case you did want to use some armor, there is one suit that a monk can wear. If you read the description for Keldorn's Armor it mentions that few others than he can wear it. Monks can wear it, if they have these stats:
Have you tried talking to him. By chance are you invisible? There needs to be some sort of dialogue before the battle can really begin and before he dies.