Moondancer spectres can only be found using Allflame Ember of Arohongui. You can check the build's timeline on poe.ninja ~ builds ~ DigginUpYoRelatives ~ Timeline. This spectre triggers a projectile spell as it moves. So any minion movement speed modifier scales the spell trigger frequency. I think It can further improved in the right hands but that's what I achieved with my limited knowledge. I can't calculate the DPS since PoB doesn't support this spectre but I think it's around 20m~

I was using 8x Moondancers + 1x Spectral Leader for more action speed but the leader kept dying.

Little trivia: My findings are that "Return Projectile Support" and "Pierce Support" actually negatively effects the clear speed since it kinda disables the explode~shotgun part of the spell. Also, as you can see they are heavily bombarding the direction I'm moving. You can cheese it by standing 2 meters from the boss, casting Arcanist Brand on it and watch Automated Convocation do it's job.

If anyone wants to try it before the league ends OR wants to get the spectre for standart here's my PoB: https://pobb.in/SmaBgxuOytq3