Mobs respawn very fast (almost straight-away) are in large groups and are very close to the next encounter so are easy agro. Because of this the large groups must be pulled like a large slow moving body pull. Perform no combat on the encounter until all have arrived. One strategy that works well is when one monster is left in the group move to a new location and body pull the next group. You must move fast to get to the names or you will be fighting multiple encounters at once as they spawn around you.
These groups are of 4 or 6 mobs. They will stop respawning shortly after subname and quest mob Maledictors nearby are killed. The 1st groups near the entrance respawn after about a minute. The 2nd sets deep in the zone respawn almost instantly. They can be mezzed or a Bruiser can train them away from you. The ^^^ Patrollers in the top level do not respawn.
The zombies at the bottom of the well stop respawning after a statue in the nearby pool is activated.
The Everburning Soul Can be pulled cleanly when the skeletons in his room depop. If you kill them they repop instantly. The Name has fear, knockback and mana drain.
The key for the shard chest will drop from a theiving jesterling, which is a very small, invisible mob found in the back-left corner of the room containing the second Maledictive terror. Spawn point = 29, -64, -137 in the Armory. He is easily missed in the mayhem of the fight!