This is something I had drawn years ago as part of an old corruption thing I was doing, you can still see the concept of it in my gallery on some old Zeix posts.

But now I'm retooling it to be a special symbol from the Obsidian Spires setting. It glows with a faint eerie purple aura, not enough to bring much light, but enough light like a very dim glowstick that's about to go out.