I finally got past the Twisted Halls today with a time of 16:09 with the Bro Mage!
I ended up combining a couple of different builds with this YouTube video providing final inspiration. Orcs Must Die! 2 - Sorceress - Solo 5 Skull (War Mage Difficulty) - 15 Twisted Halls
Used kill boxes traps right before the rifts at the bottom of the stairs on both sides as you will see in the video. But my kill boxes were tar, boom barrel dispensers, haymakers and a couple arrow walls. In each kill box I had two decoys. Until round 11 when I added two more for good measure.
At the top of stairs I built up to 4 archers with a decoy on each side by level 10 to protect from any escapees from the kill boxes and gnoll hunters.
For air support I always use decoys at the edge of the platform by the rift and start with two archers. They can take all air mobs until about round 6 or 7. And by round 9 or so I have 4 to 5 positioned behind the decoy and the rift that take out all fliers so I don't have to worry about them.
Now I just need to work on getting 50 rounds in endless and completing all the co-op achieves. My highest endless round so far is 44 on Crossfire.