Mob appears to be linked with the others in their camp. At least I had split this one out clearly, and half way through the fight his friends joined the fray. No way they picked up aggro on their own.
Amended: not true, they can be split. I use CoHero to clear aggro and this spell doesn't always do that, especially if the puller is summoned too close to the pack of mobs. The camp can be cleared but it does require capable splitting since usually all but 1 will come. Druid harmony lands but doesn't seem to work or else the assist-aggro range on these camp mobs is higher than typical.
So far everything's been mezzable but it had better land since the melee mobs in these camps hit FAST AND HARD and the casters, druids, necros and shamans, do cast some powerful spells.
Edited, Nov 3rd 2008 8:11am by Sippin