No Respawn (except for 2ish mobs). Setup camp at zone in. Pull singles with monk.
To kill door guardian trivially. Run shaman there, debuff wth malos and run then click out. repeat for cripple and slow. door guardian is a slow moving mob, runspeed 3 is enough to let you zone out withouth the rest of group getting aggro. Pull and kill guardian at zone - might have to reslow in fight. but it's easy.
when you have cleared all in the main area, use mage eye to find chest down tunnels.
Send monk in, FD, target chest. /open. FD. target chest. /loot. FD. loot key. COH with mage back or FD-run back
setup camp near unlocked door. pull and kill room, stay away from shroom.
Only mobs that respawn are the two near the shroom I think. Kill them last, and quick.
on way out couple of mobs spawn and attack. Let shroom offtank (he will live for 30 seconds vs a mob damage) while you slow other and put pally on it. Then slow the one on shroom and put monk on it. Kill monk one. kill pally 1. should be easy all in all. Use group heals/hot's from shaman, druid and pally at this stage. Oh use lassitude on monk and pally at this stage.
I 4 boxed this at 70. With 75 should be easy.