I have been reading a bit of D&D lore lately, and have a question -- aren't Shar and Selune (and Mystra and Elistrateteblabalbal the drow one) basically aspects of the same goddess? In the case of Shar and Selune, weren't they the same entity, divided in two and set against each other?
There are so many goddesses of the Moon / Magic / Night in here that it gets a bit confusing who does what and whether they are just aspects of the same force (dare I say... Absolute) or rather greedy horny independent gods like the ones in the Greek Pantheon.
On a related note, I just watched Over the Moon and I would like Larian to provide us with a Shar / Selune musical number set on the Astral Plane --- thanks, I'll go hide in a moon crater now.
Selune is the goddess of the light side of the moon.
Shar is the goddess of the dark side of the moon.
Mystril is the god of magic, created when Selune weaponised her Magic domain against Shar. Selune lost Magic and Mystril and the Weave were created. Mortal mages use the Weave (a universal magic field) to cast spells. Later, Mystril died when (I think his name was Karsis?) attempted to become One with Magic, and once the chaos settled down, Mystra formed from the Weave to replace him.
Then Mystra died in the Time of Troubles and gave her powers to a human wizard called Midnight, who took the name Mystra in honour of her predecessor.
Shar, jealous of the close friendship between Mystra and Selune, created the Shadow Weave, which can be used instead of the Weave as long as you worship Shar or can withstand the maddening effects she would otherwise shield you from. Shadow Weave magic is better at illusion, enchantment and necromancy, but much weaker at... evocation and a couple of others I can't remember off the top of my head.
So then you have the Elven Pantheon, a bunch of gods who followed the Elves to Torill when they migrated from Oerth. They brought their own moon goddess with them, Sehanine. There was a bit of negotiation, but Sehanine agreed to submit herself to Selune, becoming an aspect of the local moon deity while retaining personal autonomy.
As for Eilistraee, she's not a goddess of the moon so to speak. She's Corellion and Lolth's daughter. When Lolth went evil and took the dark elves with her, eilistraee rebelled against her mother and sided with her father. Since the Illithiri were cursed to be unable to withstand the sun's light, as the goddess of good drow Eilistraee has a lunar aspect because surface drow are only comfortable outside at night.
Of course, it's made more complicated by the fact that after the Time of Troubles, Ao (the overgod / chief deity) broke the Tablets of Fate that listed all the gods and their portfolios and domains. He decreed that gods would be powered by the belief of their worshippers instead of existing by divine right. So Sehanine gained some of her old power back, because the elves still worship her directly.
Then there's the case of many cultures having their own beliefs and names for the gods, so the Untheric people (for example) worship Nanna-sin as the god of the moon. He died a few thousand years ago, but he was recently resurrected as a non-deific immortal (Thanks, Asmodeus!) and is slowly gaining power again as the Untheric peoples devote prayers to him.
More information can be found at
https://forgottenrealms.fandom.com/wiki/Main_Page which, while a wiki, is pretty well maintained.