It’s something shamans use to create a type of “god”. They starve them and dehydrate them for days (sometimes they give them human sacrifices to eat after weeks depending on the ritual) after they die they then worship this being as if it’s a god. This is what I’ve gathered from the kdramas and manwhas I’ve read. It’s literally just used to create and control a powerful being so it can bring their family wealth or whatever they’re seeking out. But since it’s extremely immoral it’s supposed to be like a hidden or banned ritual.

Does he split rent with mugo in there?
Is it some sort of korean myth or something?! Why do they all use it?!