You begin this map staring down a long corridor that leads to a pool of lava containing a few Afrits. The portal back to Hub 3: Nave (map) is immediately to your right. The map's gear sits on a raised pedestal in the lava in the lava room.
In the lava room, there are two lit walls/floors. One at the north of the room, behind which is a lift that leads up to a window overlooking a later area of the map. You can also see the Sigil of the Magus (Mage weapon icon) from this vantage point.
The other lit edge in the lava room is over by the bars. Walk on to it and the floor will lower into a slime river. Drop down said river to find a teleporter. Using it will send you atop the pedestal that contains the map's gear.
Head back to Hub 3: Nave (map) to place the gear.
Return To Abattoir
After having placed the gear, a bridge in the lava room will raise leading to the other pedestal in the room, which contains a switch you have to reach and press.
To access this switch return to the long corridor and note the two lit walls. Behind both of these are stairs, though one is initially blocked. Head up the one that isn't to find a small platform to jump up on at the end. Around the corner of this platform is a switch that will unblock the other stairs. The ceiling of the platform is also a crusher that will activate a couple of seconds after you press the switch, so get off quickly.
Head up the now unblocked stairs and take a right. Continuing straight ahead would lead to a room that contains a couple of artifacts and a few Stalkers. Carry on down this corridor, noting the large square pillar in the middle of a small room part way down it and the locked door to the right of it. Eventually you will come to a room with a pair of switches. Approaching the switches will open several marked pens of Ettins along the right side of the room.
Quick players can head to the left switch at this point and press it to activate crushers at the entrances to the pens. The right switch opens the aforementioned locked door and large square pillar, revealing several more Ettins. Behind the locked door is the bridge you are aiming to reach. However to complicate matters, the corridor between you and it is now full of crushing ceilings. Cross the bridge and press the switch to open a door back at the start of the map.
Return to the start and enter the door to the newly revealed room and travel to its top left side. You are now passing between two windows you may have looked out from/into earlier. In the next room is a large number of Reivers and a small river of slime containing a few Stalkers.
In the far corner of the room is a hole at the bottom of which is a Stalker and another switch. Drop down and press the switch to raise the slime at the bottom of the hole. This also opens bars in the lava room next to the lowering lit floor.
Behind these bars is a teleporter, which will take you to a small room containing the Mage weapon icon and a portal back to Hub 3: Dark Watch. You are done with this map.