I really like the slightly different shading on the cavern wall, it makes that part appear gloomier, very cool. Of course I would probably chuck in some dirt and rubble in the corners. Stuff will probably collect there, especially since the apprentice doesn't have an apprentice to sweep up!

Also kudos for making the map big. I really like having extra room to play with on battlemaps and this map offers the possibility of very mobile encounters that "range all over"!

cheers,
Meshon