But I have no idea what it is! Any ID? I am sure it is a predator, it seems like the bulbous tentacles are used to catch prey? In one of the photos it is clear it had ingested a copepod.

4x, slightly cropped, BF

4x, slightly cropped, FLUO-C4

10x, DIC

10x, FLUO-C4, ingested copepod

20x, FLUO-C4, looks like tiny little light bulbs under UV/Blue excitation.