Does exactly what it says on the tin.
To quote the UA infomercial “The Brainworx bx_refinement plug-in for UAD-2 and Apollo tastefully removes the harsh, hard edges of your tracks without dramatically altering the character and tone of your source material.” And IME that’s exactly what it does, even when used in a voice-over chain following Soothe 2 and / or Spiff, where you might perhaps not necessarily have expected it to add so much to the overall result. Extremely useful plugin!