What to do with this new information!
Papyrus assumes (or hope) that Undyne is a skeleton, thus why he pictures her as one,haha.
Lot of red hats in the underground, come to think of it.
The magic poster just talks about the various soul magics, so like, blue magic makes the soul affected by gravity, green makes it so you can't escape, purple traps you on three rails, yellow lets you shoot magic bullets, that think of it.