Witchaven/Level 18

From the start, head to the square central structure and up the stairs to the corner entrance, where Illwhyrin makes another appearance. The arrow-ladder trick can help you get in here, then you can battle your way to the brass key. The brass key door is to the east of this structure, and through it, the black key can be found in the first chamber on the left.

Go to the southeast of the big square, where a section of floor lowers, and descend into the area that's revealed. You will want to head to the water area where there are many pillars, and locate the pentagram before returning. You will have to fly to get back out; a few scrolls can be found in this region.

Once you have the pentagram, head to the southwest area where the black key door is. The exit is just beyond the door, guarded by a couple of Mino Drakes.

Bonus Areas

 * Towards the back of the area that's locked with the brass key, you can use the pull chains to raise stairs to the far back of the area. Another pull chain there will open the middle structure, which contains a morning star and sapphire ring. Be careful, however, as it is possible to become trapped in the back area.