Galaxy Eater

From itch.io: The galaxy eater doesn't apply to the logic of our world or dimension. Tearing through a gateway into a trepid world of despair, it now feasts on the dwindling sanity of anyone foolish enough to cross its path. Largely incorporeal, it is difficult for the lacklustre mind of your average dungeon diver to conceive such a creature, building on images one has seen before in the real world, leaves too many cracks and can shatter the mind. The galaxy eater will follow the PC's until it has drained them of their sanity. It will not attack physically but mentally instead. Unleashing a torrent of horror into their psyche like a festering untreated wound. It isn't set in stone where the galaxy eater will appear, he could manifest in a random cave or dungeon, even on the streets of Galgenbeck. Regardless, he will appear and he will devour the galaxy.