to your theory about massless magic, since monsters and their magic are made of the same thing, i can come up with a reason or two on why magic isnt massless, for one, monsters do things that need mass, for example, lifting something, walking or running, and i doubt a monster being massless would make to much sense physically anyways.

Description: full name: sans comic skeleton full pam name: john sans classic sprite sheet made by spectator/scott the watcher (thank you its so good) (some sprites were put together by me, like the fire engulfed sprites, and i did edit some sprites to be more dynamic, but mostly all credit goes to scott.)