Welcome to Enclavum Barross.
The skull here is located after the second heal station.
On one of the drop points you will see four valves, each of these valves is hooked to two pipes and will rotate the pipes when you spin the valves. Your goal is to connect the bottom left corner to the bottom right. Keep two things in mind while spinning the valves.
1: all the pipes are used in the solution, its a bit curvy.
2: the ones linked to both a straight pipe and a bend really only have two possible positions because the one on the left has to be horizontal, and the one on the right has to be vertical.
Get the pipes to connect and the door below will open, Inside is the Martyrs skull, you now have the skull and the plasteel, gratz, bye.
![](https://i.ytimg.com/vi/od_jK-qautw/mqdefault.jpg)