When you enter and get to the first fork in the corridor, take the door to the right. The door directly ahead leads to a room whose exit is jammed shut, so you cant go that way anyway. On your right, there will be a stairway leading downward (with guards at the bottom). Once down there, head south and take the north fork. This passage leads around to a switch which will open the door back on the starting room. The south fork leads to a chest which contains a flute. (What to do with flute?) On your way back, be wary of the west exit from the bottom of the ramp: That leads down to a water channel. In the water are several kinds of oozes -- all of which will devour your items and tend to be immune to such items. Just avoid. And dont fall in the lake; youll have plenty of chances to do so. Back upstairs, head through the south door and continue to a platform with a lever. This lever operates an elevator down (to some more waiting guards). From here, around the corner and to the north is another switch. This switch opens a secret door back down the corridor that leads to some flour sacks containing food and a chest. In the chest is a letter linking the Dragoon raiders with the Shadow Guild. If you return with this letter to New Sorigal city hall, you will receive a 5000gp reward. Continuing down the corridor, over the bridge, straight, and over another bridge is another button. This will open a door that you skipped by. Head back over the bridge and turn left (east) at the fork between the bridges and into the next room. The exit to this room is controlled by that switch. Almost there -- after going down the second elevator, follow the large passage all of the way to the end. There will be six chests against the far wall. Only the middle-left chest (#2) is real; touching any of the other chests will teleport you to another area of the labyrinth. Inside this chest is a harp, which is needed to solve quest 8.
Through the door, you will reach a tiny room with a lever on both sides of the door. This is an elevator room -- pulling the lever will lower you way down to the bottom, where another door waits. This door requires that you have the key to Ghariks Laboratory. You can get this key from the Silver Helm Outpost on the Misty Islands. In the next room (which is a nasty fight), go through the wall on the far door, and then up the spiral ramp around the edge of the next room. Up there, you need only fight your way across one more bridge and then through the last group of warlocks in the room on the far side. The chest against the far wall contains the Hourglass of Time needed to complete quest 12.