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
Coinlake sits perched between two sheer cliffs in the Stigrani range, and is difficult to find, much less approach. Four miles long and two across, the water is a vibrant cyan blue. The lake's shoreline is an unassuming beach of gray pebbles, and its mean depth is seventy feet. The rare times when the sun makes its way between the cliffs and shines over the the still water, one could see clearly the lake's rock-strewn bottom.
Strangely, no fish or aquatic life can be found here.
At night, a peculiar phenomena occurs. When the night sky is clear, the moon and stars are reflected in the lake's surface, but if one were to look at the surface from a high vantage point, the reflection does not match the firmament above!
Instead the water's surface reflects the night sky of some other distant world and seventeen shining golden moons besides, each ones shimmering upon the water like so many gold coins!
Legends whisper that Coinlake is not a lake at all, but a gate or nexus, to some distant alien world.
The mystery has long remained unsolved, and only recently has the Arch-Duke commissioned an expedition to uncover the secret of Coinlake once and for all. Among the team members are several scholars of the Nascent Academy, an astrologer from the Occultists Guild, and of course the PCs, acting as body guards.