This is the Lair of the Sorcerer's Apprentice. Beekham had not considered just how old Trell the Sorcerer was when he won an apprenticeship with him. The first 6 months had passed as expected for a young mage apprentice, lots of drudge work, a little bit of magic. He was just reaching the point where Trell was starting to teach him some real magic when the worst possible thing happened. Trell went to bed and did not wake up. It was not fair that Trell died leaving Beekham so untrained. But that did not stop the young wizard. Now he had access to all of Trell's books and equipment. Beekham started to experiment, to teach himself. That's where things went bad. Beekham became obsessed, he lacked guidance and wisdom, and he tried any kind of magic he thought he could learn. It was bad enough when some of his experiments got loose, but when he started sacrificing people from the nearby village, the villagers decided they needed to get rid of him. The village hired a group of adventurers to rid them of this young sorcerer before he does more damage. The lair is a few miles out of town. The adventurers are given a key to unlock the main door by an old farmer who had been Trell's friend. Unfortunately neither he nor anyone else had ever been inside, so the layout of the lair is unknown.
Beekham has seven 2nd Lvl Kenku who are his guards and workers. In addition to them, he has summoned numerous low level creatures such as Fire Snakes, Mephits, Imps, Gremlins, and a homunculous. ( the DM can substitute whatever summoned creatures he wishes ) Trell only has control over the homunculous, all the others are randomly roaming around causing trouble.
The entryway is trapped. Inside the guardroom is a lever. It has three obvious positions and one secret one. The guards can set the lever to Off, Portcullis On, and Portcullis and Sleep Gas On. If the trap is active any one who crosses the greenish bar on the hall floor will cause a portcullis to drop down and lock at either end of the hall. If the sleep gas is on also then if anyone crosses over the skull barrier it will cause the hall to fill with Sleep gas. (Save vs poison to avoid the sleep gas) Once the traps have been triggered the portcullis can only be released by a lever inside the Octagonal room.
There is a secondary entrance. Following the stream into it's tunnel will lead into the large cave. Keep in mind that the water is flowing out of the cave through a heavy iron grate. The gate is fixed in place and does not normally open.