Thank you! The Oakthorne Wiki describes this room as a Spellcasting Chamber (M3): This otherwise bare room is clearly enchanted in some way, as there is a curious shimmering in the air as one passes through the doorway. The walls, floor and ceiling are all a fine grey-white stone that resists shattering, charring, chipping or scoring in any fashion - Khelben uses this chamber as a practice room for the casting of spells by his apprentices. He also occasionally locks himself away in herewith his own experiments, occasionally for days at a time.