Blizzard has added two new faction-favored companions, the Festival Lantern (Horde) and the Lunar Lantern (Alliance), to this in-game event. Don't let a faction tag discourage you, though! Both companions are Bind On Use, which means that a single character can acquire and add both pets to their collection.
Players can purchase these pets from Valadar Starsong, located in Moonglade. Each lantern costs 50 Coins of Ancestry.