Build Apprentice towers in-wave. Auras and Buff Beams in 1st wave buildphase.
(1) Build marker 1 buff beam from the bottom to the top of the stairs. Place 3 LT on the top part for better chains. DST can go anywhere on that buff, so long as they are pointed at 45 degree angles, going clockwise from South (S, SW, W, NW, N, NE, E)
(2) Build marker 2 buff beam on the bridge, as close to the main core as possible. 2 DSTs facing directly South and an LT.
(3) Stand TB on marker 3. Boosts both stacks.
Splitting the stacks lets you spawnkill slowgres at the end of the wave.
Only need to upgrade buffs. Electric auras should kill the trash.