This is a 2-stack, 2 Tower Boost build, focus is on speed by dropping the goblin copters that tend to drag the wave on. North is pretty well controlled by the Mortar and oil and web, South middle is controlled by placing traps.
Aiming the TB monks at the neaby Goblin Copter Spawns was best spot to keep TB up for the whole wave. Other spawns get intermittent near the end.
Hint 3: These traps and buff beam are on the upper level
2 TB, 2 summoners
Test run combat time 34:04, had some broken waves, not the best, still working it out
total mobs - 18,004 ~529 kills/min
Test run #2 - 32:21 Combat
Test run 3 - 30:31 Combat (changed a lot and got both TB to stay up full wave)
Last test run - 29:25 combat time (cookin') = 612 kills/min