A nifty little encounter appropriate for any powerful sorcerer/magically adept monsters lair.
When the party have penetrated to an appropriatly impressive level/room they encounter The Door, this door is a vessel through which the Sorcerer/Monster can safely work against any intruders, the door is heavy duty iron bound studded oak wrought with craft skill and magic, set in the middle is a crystal orb, once the party get within a preset distance the orb flickers briefly as the door warns its "master" of the intruders, the master can then effectivly possess the door itself, this means that all movement the door is capable of (i.e. opening and closing) come under the control of the master, the master can also cast spells from the door as if he were there himself, all the while any damage that is inflicted in return merely damages the door, this will in effect ruin any of the parties chances of surprise, allow the master to assess the parties abilities while remaining safe and sound and finally will probably cause the party to waste some of their juicier items/spells on a chunk of wood and iron, and if the master happens to have a deadly spell or three it could also reduce the size of the party,
Of course if you wanted to be really nasty you could have the door open to admit one person and then slam shut on the second person (squish) whilst blasting away with every spell in the mastrs repetoir
THE GNOMES OF UDNALOR: Part II
Having left the hush of the upper halls, and crossed the depths of the Braeth (an underground river, which is not all that deep because bear in mind we're talking about gnomes here), you would find yourself in Wattling Street, the main road through Udnalor. It's actually a long, well-worn passageway which opens out eventually into the City Centre. The gnome-buildings branch off Wattling Street as small burrows or caverns with boulder-blocked doorways for privacy. You can find armourers and smiths (though their armour tends to be on the small side for humans to buy) and many other types of trader.
There are many streets, ginnels and cooies which run off Wattling Street, the most famous probably being Smell Street, the domain of the infamous gnomish alchemists, the eponymous smell being very distinctive: the stench of cooking fungus, the aroma of subterranean spices, the pungent reek of rotting carcasses (used in some of the more notorious experiments). An encounter with an alchemist can really be spiced up (excuse the pun) if you have a well-stocked herb cupboard, and actually make up the potions, elixirs and draughts as they are ordered by characters.