These are spawned (along with these guys: Lost Souls) whenever someone (or some thing) on your side dies in the fight agaist the REAL Jeplak, Lord of Srerendi. I say "some thing" because this includes PETS (you might want to hold the leash on all those AA pets during this fight, hehe). This restriction applies even after the named is down - you have to kill all these adds without dying to have a clean fight.
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By themselves, these aren't so tough. They hit for a max around 300, they don't have any more HP than the stuff by the zone-in, and they are straight melee. Slowable, nukeable, rootable/snareable, they're only hard because there can be LOTS of them, and they swarm to whomever has the lowest health like sharks. Kite them, pick them off one by one (or just AoE bomb them, hehe), and they're raid exp. Enjoy!