4 reflects around the square, 3 small physical beams (2DU, 2DU, and 3 DU) from the big pillars to close in that approach (give yourself as much space as you can for the forest ogres). 6 DU buff beam reaching out, so your towers can catch it in the corner, and your minions (3 Harbingers is about equal to 7..so don't stress on that, but keep spiders and mages off the buff beam) can catch it outside the wire.

Added extra slow auras to help stablity, seemed to work.
Added darkness trap to further reduce the damage from close up mobs.

Build walls and reflects and warden and hermit, then as much guardian as you can.  Some later wave bring in your summoner builder and throw out the harbingers (they help draw agro and drop big guys/bosses when they get close).

Party: 1 TB monk, 1 summoner with squire/huntress pets (on owls), 1 summoner with monk/huntress pets (on warden stuff)
Until upped, have your upgrader out, then once you're maxed, can swap to DPS shooter for the final wave, mostly to drop the annoyingly high health and distant mega copters.

Typical time is between 20-23 mins based on RNG.  Nightmare same build was about 2 mins faster (around 19 mins), but was also WAY easier to run, low pressure, could modify quite a bit probly.

I ran it without any DPS (had another summoner with monk/huntress pet in), and it was not any slower.  The RNG of the trick or treaters is the biggest factor on time.  All the heals/buffs at the main spot keep your health up no matter what comes chomping at you.

The only time we lose is to Forest Ogres trick or treating, really got to watch out your team is far enough away that they can't get slapped and fly away.