Waning Moon is an Uncommon Fortnite Spray. Waning Moon was available via the Battle Pass during Season 19 and could be unlocked on Page 3 and costs 4 Battle Stars.
How-to Get the Waning Moon Spray
Waning Moon is part of Season 19. If that season is still currently in the game, you can obtain this item by purchasing and/or leveling up your Battle Pass.