Umbra

Umbra is easy to mix up with Penumbra, an aura with a similar name and an identical rarity, so check the symbol before you celebrate. This one is Epic, 1 in 1,010, added in Eon 1-23 and credited to reeseyhi. Without luck that is about a thousand rolls; with 10x it drops to roughly 101, which makes it one of the more reachable Epic auras and not tied to any biome or event.

According to the Sol's RNG Wiki, the player keeps the default Roblox animation and gets a tiny black glint where the eyes are. On the torso sits the Chinese character 衡, meaning balance, which pulls in black specks while small flickers of black electricity play around the body. The cutscene is plain: the screen fades to black and a grey glow along the bottom edge reveals the name in Playfair Display type.

The wiki points out the naming logic. An umbra is the darkest part of a shadow, which explains the dark palette, and the balance symbol links it conceptually to Penumbra.