Story Idea #9 · 6:29am Jan 20th, 2016
The portal between the human world and Equestria run's, or ran, on the lunar cycle, sort of. So, who's to say that the Rainboom's Equestrian magic doesn't react to the lunar cycle in its own way.
If you use this concept in one of your own fics, or you know of a fic that already uses this concept, please link me to it.