The build is actually pretty simple: Since we are aiming for low stat farm, we need 2 stacks, 1 at each crystal. Place Deadly strike towers(DST) facing each spawn(including goblin copter spawn)

Hint 2 is at top crystal(next to forge) build 4 dst facing the spawns on the 5du buff beam(you can do it 4 if you stack but wouldn't matter anyway). After and if you get the increased DU upgrade, place 2 more dst facing goblin copter spawn (west and northeast).

Hint 1 is at the bottom crystal build 5 dst facing spawns and one facing north(the djinn spawn)

So, works with 4 people no boost/guardian summoner required but surely will make it faster. If you got 4k+ stats you only need to upgrade buff beam.