Hollow Knight: Godhome - Lost Kin (Hitless/Radiant)
For those who don't know what Radiant means: you get hit once, you die. Took me around 15 minutes to get this down. Had much more issues with the dual bullet hell flies. Haven't bothered with getting the unbreakable strength charm so this is without it. Strongly recommend getting it if you're struggling.
If you get in a tight situation in this fight try using shade soul to knock the boss away to make some spacing. That helps with dealing with the fiery blobs.