Note 1: The green dashed line is referred to as "Center Line" when positioning tower direction.

Note 2: "X" refers to a tower stack shared by more than one builder. To achieve this, bring in an alt(s) with the second builder, and pre-place all towers in the same way you would normally tower stack, then build.

Note 3: Black Arrows = Mortar, Blue Arrows = Cloud, Green Arrow = Seed Bomb, Yellow Arrow = S.A.M.

Note 4: See Hero locations for waves below, maxed upgrades required. Range Stat on all builders required for this build.

Non-Stacked prep:

1st Str Drain on edge of lower ledge

2nd Str Drain on the Top of Stairs

4 DU beam from South Box to the edge of the lower ledge

1 Du reflect on South Ledge

4 DU beam above forge across East to West

1 Du reflect on North Castle Bulwork

2 (2) DU Web Walls on Furthest E/W spawns angled NE/NW

Pylon Catching N and S Str Drain and encompassing N Buff Beam corners

South Beam (6 total Towers):

2 Mortar X 1 Mushroom on South Ledge: Mortars Southern range edge direction should hit the Center Line

2 Wisp, 1 Shroom Pit on the upper box

North Beam (10 Total):

2 Mortars, one on the far East and West sides, with the North range edge direction hitting the Center Line

--Need 3 Heroes out for the Below--

1 Seed Bomb  X 1 Mushroom X 1 S.A.M. X 1 Shroom Pit X 4 Cloud Towers

Seed Bomb Due North, S.A.M. Due South

NE Cloud Tower is pointed between NE Spawns, NW Cloud Tower is pointed between NW Spawns

SE/SW Cloud Towers range edge direction touches Southern Centerline 

Heroes in Wave:

TB (7.3k) Standing centerline between Crystals, aiming Due East 30 with a slight Angle South

Range x Rate Summoner On South Stack

Rate x Rate Summoner North Stack

Tower Squire by Pylon

This build took a few days to make concrete and took quite a bit of testing with mortar's effective range vs stated range (Web Walls make this doable).

The Goal of this build was to spawn kill with mortars, and copter/wyvern spawn killing with S.A.M./Cloud Towers. This build abuses the long sightlines provided by building on the North end facing South, so that there are no grounded Mobs to steal Agro.

My best time is right at 30 minutes of combat, I'm sure, with better stats that can be improved. I hope this speeds up your late-game armor farming. Good luck!