If your in an aq20 group and your group downs at least the second boss then all the mobs up to him do not respawn after a soft reset, aka 30 minutes. But, the scarab coffers do respawn along with the level 55 non-elite scarabs. So spam around and buy as many Scarab Coffer Keys as you can and then when you go on your aq20 run stay after the run is called and after 30 minutes of no one being inside the instance the scarab coffers respawn. You take your key and take them all for yourself. Typically you get one idol and 11-15 scarabs.