Actually it's pretty easy once you know what to do. You spawn the echo. Jump up onto the opposite ledge. 4 Taken Phalaxes spawn, try and take down as many as possible. Then to your right, there is a taken spawner orb. Kill the Taken Psions it's spawns then destroy the spawner orb. This stops it from spawning more enemies. Before you start shooting the echo, run around and activate the taken mines. This will make it easier in the long run when you might need to run away. Then shoot the echo until despawns from the same ledge which you started. Then 2 spawning orbs will appear and 2 (I think) Taken Minotaurs will spawn in the middle. Kill them as soon as you can. Then destroy the summoning orbs along with the goblins and Psions. The Psions spawn to the orb to the right and the goblins spawn across the other side of the room. Once you have done this, run around and activate all the mines again. Then proceed to taking down the echos health again. The final stage will see 2 (or 4, I can't remember) Taken Centurions in the middle. Try and kill them as quickly as possible. Four summoning orbs will appear. Psions to your right, Goblins across the room and Acolytes to your left. Kill the enemies and destroy every orb. It's pretty much a clear finish because you only have to worry about the echo here on out. Hope this has helped and anyone else who needed it. I done it with this method with 282 light.