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Nature-worshiping Elves is really a cliche at this point but by using other religions like those below it's possible to make it less cliche. The cult of Nature preaches harmony with the natural world, preservation of natural beauty/resources and the rejection of "excessive" technology and artificial methods of altering the land. Societies where Nature is the main deity tend to be reactive, only acting militarily when their territories are directly threatened by outsiders' expansion.
"Damn it feels good to be an Elf." The cult of the Ur-Elf deifies, exaggerates, and worships the traits of the Elvish race. It can shoot better than the god of archery, sneak up on the god of sneaking, out-magic the god of magic, and out-swordplay the god of swordplay. You can do all these things too if you're an Elf! (Not Really.) The Ur-Elf (who was going to be named "Amys") is essentially a god of egotism and self-adulation. It was my conception that Amys would be portrayed as genderless, male, female, and/or hermaphroditic depending on the temple in question and local traditions to express the universality of Elvish awesomeness. Inspired by Heedless One, the statues of the Ur-Elf would be made of emerald or jade but now this idea seems a little silly to me. Unlike the Nature worshipers (see above), the Ur-Elf religion encourages aggressive expansion and conquest. I also was thinking that magic in a society dominated by Ur-Elf religion would be stagnant as the leading mages would only care about ye olde Elven magic and not any of that non-Elf witchery.
Since Elves are traditionally forest-dwellers and fires can destroy forests, it seems weird to me that no one seems to have examined the Elvish view of fire. I did toy around with the idea of giving all Elves pyrophobia one time but it seems like something that would work in a story not a game. Anyway, Fire-cults worship and appease powers of fire in an effort to ward off forest fires in particular and all dangerous fire in general. They practice ceremonial burnings of effigies and objects to "feed" the fire so that it won't be "hungry" and burn the environs. They also dance around fires and with torches. While on inside of the group this all seems on the level, mainstream Elvish society sees a bunch of nascent arsonist whackos only a single step away from burning down the city. For this reason, most public Fire-cults are in non-Elven lands.
Much like Nature-worshiping Elves, Elves as the masters of magic is a bit of a cliche too. Elves who worship Magic are viewed by almost all Elvish societies as dangerous loners due to their obsession with power and immortality. It's the goal of many to transcend into something else via magic, something that isn't part of the natural order (so Nature-worshipers don't like it) and which implies that Elves aren't the best creatures ever (so Ur-Elf worshipers don't like it). Magic-worshipers tend to be wizards. They also tend to be found almost exclusively in non-Elf settlements, usually as founders and teachers in magical academies or employed in the government/military.
No, not Batman. "The Bat" is a title used when referring to the Elves' god of curses, night, and caves, who is represented by a bat. Similar to the Fire-cults above, worship of The Bat was mainly intended to ward off curses but there were also plenty of curse-mages for hire, which led to a violent suppression of the cults by major Elvish society. I imagined that the worshipers of this deity eventually became wandering Gypsy/carnival analogues who used Elvish skills and magic to entertain the masses. Another idea that I never really expanded is that one of The Bat's major curses is the origin of vampirism.