The way it should work is fairly simple:
Encounter Ends / Starts -> Everyone on Conveyor Belt should be teleported down to Main Platform.
The behaviour between Main Platform and Conveyor belt should be something similar to smoke bomb effect (so if rogue tries to use shadowstep from Main Platform to Conveyor / Vice Versa, then he should receive error message: "your Vision of the target is obscured");
Once a wave of weapons reaches the end of belt - Blackfuse should pull all players standing on it back to main platform. There should be total of 12 waves of weapons, with 13th being special berserk weapons to wipe the raid.
About Demonic Circles: