I propose an increase in difficulty to the Collector mini-boss in the form of AI-controlled Battle Sprite attacks.
Enemy Sprites scale from stage 1 to 3 depending on Tier, and are colored dark grey/white/red, sharing the Collector's palette.
Enemy sprites are summoned by the Collector, and use their first skills as a form of attack. Their AI is a modified Greaver's; they swoop down a distance away from the target and fire somewhat-inaccurately, effectively creating a "bullet hell" when two or more enemy sprites are present.
Enemy sprites can be "killed", and will fly off akin to Snipes when their health is depleted.
Enemy sprites can be of any type introduced, even promotional ones, but all share the same palette as the Collector. Their harnesses are re-skinned with the sigil of the Collector, seen on its back.

To top it all off, I propose an increase in Collector sightings in the Clockworks as well as a promo box with Collector-paletted costumes, accessories, and Sprites.