New Menaces: Yearning, Burning?

How does one acquire this? It’s noted when you travel to the surface, and it sounds like something that might dissuade me from filling up 30 mirrorcatch boxes at once but so far I haven’t gotten it.

I don’t think it’s fully implemented yet (at least, it wasn’t when downloaded the update), but it’s a sunlight-related menace.

It appears to be tied to the Go East storyline.

Mmm. So best stock up on echoes now, eh?