Wharf boss challenge

How do I do this? He doesn't summon enough orbs. The most I've ever seen is 5. I'm here kiting this guy for 5 minutes waiting to get more, but it never happens.

EDIT: I've damaged him little by little, all the way to culling range. Did this on an 8mod T16 Wharf from Zana mission.

This sounds like a twinned challenge to me, whenever it involves dicking about with a boss spawning all their mechanics its usually a twinned challenge.

Ended up doing it twinned. Thanks for the suggestion. Still a bad challenge. damn they expect me to count this out and make sure there are 15 orbs and not 14? That was eye cancer

I've yet to successfully do this challenge, not for counting issues as I clear the rest of the map and use the monster counter in the corner, but because my ice traps clear too much of the screen at once. Is there a recommended skill that can kill a mob in a pack of mobs or is this challenge done by separating and kiting only?

You can use any skill, just kite and drag the boss away from the pack.