Year 4 and I still haven't found the prismatic jelly. I suppose it's dropped by slimes but I've killed almost 1000 and nothing, which makes me think it's a special monster drop, maybe some sort of "boss" that I have to search for.

Oh, I just realized that it's probably in the level 100 at the Skull Caves and that's why there's a quest to go there. Yeah, it's gotta be it.

Time to stock up on bombs and staircases. Level 100 here I go.