ok, i hunt in this zone, and i hav found some info needs to be cleared up.
These guys are not placeholders for the swarm leader. Kill four of the swarmcallers, and the swarm leader will randomly spawn in the zone.
To a lvl 26, they can con from dark blue to red. It varies, though usually they are either black or dark Blue.
They do regen pretty well, and hit for decent dmg. Though my 26 mage can solo just about anything in the zone one vs one(+pet) except guards, swarm leader, and trog king.