I have a few ideas. Hope you like small floaty glowy things…
1. Fireflies. I know we already have the White Glow effect, but I was thinking something much more localized to the character's immediate vicinity (iirc White Glow reaches up to a crazy 6 cells away in all directions, which is visually distracting), and more true to what fireflies look like in real life. The effect could come in white, yellow, yellow-green, and yellow-orange color variants.
2. A starry sky. Something similar to Cosmic Connection, but the empty space part would not be visible in favor of more of a focus on the stars and constellations. Maybe there could even be tiny shooting stars.
3. Will-of-the-wisps. Three(?) tiny Horongs floating around the player in a similar, or even the same, pattern as the effect from the Doram passive skill Sprite Marble. (In fact I would absolutely not mind if they directly overlapped and entirely covered up that effect...)
4. Glowing floating jellyfish. Could also be three jellyfish and follow the Sprite Marble movement pattern.
5. Floating lanterns. Again, could be three lanterns and follow the Sprite Marble movement pattern.
6. Fire and embers, rising upwards before disappearing.
I hope any of these ideas are useful 🙂