One this I see is the hackers sitting outside o3, teleporting in after the mini or boss is dead, then collecting the loot. I see a few ways to solve this issue.
A. spawn in temporary monsters that insta kill anything outside the locked boss zone after 20 seconds.
B. Turn the floor into 1000 DPS lava floor after the boss zone gets locked
I dont code, but maybe it wouldnt be very hard to copy and past the lava spawner from LOD that triggers at the specific stage.