Selunius
Selunius is the chosen name of the gargantuan Ancient Lunar Dragon that has claimed Selune, the moon orbiting Toril as her territory for millennia. None know what her original name was, only that she has taken on the name of the goddess of the moon in vanity, believing herself to be the true deity worthy of lunar worship. Insatiably greedy, incredibly xenophobic, and dangerously narcissistic, Selunius has built an incredibly devoted cult to worship her as a god and cater to her every whim. Like all lunar dragons she is obsessed with the phases of the moon and light/dark symbolism, so she hoards treasures such as silver, pearls, black diamonds, and magical artifacts that specifically deal with changes in alignment.
Selunius has been a threat to all spelljamming ships in the region for as long as anyone can remember, she often torments crews before she destroys the ships, taking those who bow to her as cult members if they cleanse their own ship of nonbelievers. Her lair is surrounded by hundreds of vessels that have been irreparably damaged and her hoard is decorated with a wealth of spelljamming helms kept as trophies. With the settlement of Arnesport as a city on the far side of the moon she saw an opportunity to passively grow her hoard as well as build her cult following. Each month Arnesport delivers a barge of treasure as well as anything else she requests and in return she doesn't destroy the city for the fourth time. Already a city catering to unscrupulous folk such as pirates and mercenaries, it has also become a constant source of new cultists to join her ranks as she aims to ascend to true godhood. Her cult is known to be infested with lycanthropy, a "gift" that Selunius bestows upon her favorite faithful.
Little else is known about the ancient dragon as the cult is an impenetrable black hole from which none have returned, and those who claim to have seen the dragon say she is invisible, invulnerable, and potentially omnipotent. Every few hundred years she hatches a new brood of wyrmlings which ruthlessly vie for dominance amongst themselves before they are sent off to dominate moons of their own. Her sworn enemy is the Ancient Solar Dragon at the center of the system, which she aims to destroy upon attaining true godhood.
Selunius resides in the original House of Selune, believed to be the seat of power for the Goddess Selune when she graces the material plane with her presence. The temple has been ruined and all of the iconography defaced and replaced with images of Selunius herself as she believes herself to be the one true Lunar Goddess. Her horde is suspended in a frozen pit beneath the opening of the caldera of the mountain in magical ice that only she can manipulate. Her mere presence creates a dangerous black frost that creeps across the lunar wastes, a maddening howl on the wind, and her wingbeats leave behind moon devils; swirling tornadoes of lunar regolith that freeze any who approach her lair.
