If you are talking about the nightmare puzzle the solution is 1,3,3,4,4,2,1,2,3
If your talking about the other puzzle, I've got a solution on paper drawn so I can't exactly give you that but the hint is, you need to reach the 2nd room (12 rooms in total left-to-right top-to-bottom). You want to walk into the TOP-RIGHT teleporting circle in the 2nd room to win.
I would really like to know how to get the elite and epic bosses in Chp 6. cause I can't find them. Also I hear people talking about Dark Messiah but I can't find him either.
EDIT: Oh and the Decimation is in the very top right of the map outside Kar'gath in the red area. It is under a fire elemental and the dig is hard to see cause of all the red, try angling or rotating your camera. It is literally as far top-right as you can go without stepping into the fire.