Witchaven/Level 6

Go forward from the start. It's quickest to go straight, but if you fall into the drop-down to the left, it will lead you to the same place.

You'll reach a room with a skylight and a door to the west which you should head through. At the branch you come to, south leads to the pentagram, and north to the black key. Heading for the pentagram first, there is a translucent floor, which is a spike pit. The best way to get past is to crouch and shoot several arrows into the wall over the pit to make a bridge for walking across. You'll come to a large chamber with the pentagram on a pedestal. Taking it will open chambers containing ogres and lava fiends, as well as some items.

Now go back for the black key. Again, using the bow to make a bridge is the best way across the trap pit. The black key chamber is nearly identical in layout to the one that had the pentagram, though the monster and item assortment is a bit different.

Go back to the room with the skylight and drop down into the south side. Find an illusionary wall that's translucent and head through, down the stairs that lower. You will reach a large room with a fire pit in the middle and many side chambers which open if the dark sections of floor near the fire pit are stepped on. These side chambers are full of green goblins and red ogres, so be ready for a fight.

Through the black key door, you will find a bridge with pits of deadly spikes on either side. On the far end, Illwhyrin will appear for the first time. However, she teleports away when sufficiently injured. The exit pad is across a lava pit, so you might need fire resistance or flight to cross unscathed.

Bonus Areas

 * A secret area opens behind your start position when you move forward. It contains some monsters, a quiver and a scroll
 * If you follow the drop-down immediately in front of the start, you can find a pull chain that will reveal a chamber with some potions. Don't pull the chain behind the potions, it lowers the ceiling which could crush you, and closes off the potion niche.
 * If you take the high path directly in front of the start, check the north angled wall; it is a secret door leading to potions, arrows, and both diamond and adamantine rings.