Tips for Level 17
For the upper entrances block the two sets of stairs nearest the rift. Then block around the grinder pits so they have to do a winding path through them.
In the bottom area block one side so they go around then create your standard chokepoint kill box.
Trap the top however you can once the low chokepoint killbox is in place. I used mostly brimstone and ballista since they can shoot into the middle.
I used Kelsey (for the shotgun) and took the Bladestaff with me. Freeze then kill heavies with the shotgun. Defeat massed lesser enemies with the Bladestaff. I personally fully kill upper waves for most of the run.