Witchaven/Level 24

From the start, head left, and you will soon find a side passage away from the central tower. Follow it to find a raised grey stone platform. Immmediately turn left, then left again and up the stairs. To your right, you'll find a small passage in the corner where there are white stones with vines on them, which can be revealed by a nearby floor pad. Follow it. You will find a garden of sorts, with many square pillars. Head to the end of this area where you will find a wall that lowers, and in this area you will discover the black key guarded by a dragon.

For the pentagram, return to the dark grey stone platform and head to the other side of it, near the big face on the wall, to find a smaller platform with a teleport. Warp through and go through the doors, following stairs up, then down. The pentagram is nestled in the crook of the downward stairs.

Now follow the nearby teleport back to the central area, and approach the wall of dark grey stone to lower it, revealing a lava area. Cross and find a trap-laden room on the other side. Through the black key door you will find the exit chamber, with lots of supplies to refresh you for the final battle.

Bonus Areas

 * In the area just before the black key door, there's a row of items floating in the air. Get them right away as there's a trap pad that will block them off if you're not careful. They can be reached by flying.