Amulets of Draconic Wrath

This necklace is composed of a series of amulets set with five distinctly colored jewels, each representing the five heads of the Dragon Queen Tiamat. As a bonus action the wearer can select the blue, red, black, green, or white gemstone and grip it tightly while invoking the mighty goddess of dragons. The amulet will then imbue the user with the essence of a wrathful chromatic dragon -based on the jewel selected- for one minute. Until the enchantment ends, as an action the user can spread its jaws and spew magical energy forth in a 15-foot cone. Each creature in that area must make a DC 15 Dexterity saving throw, taking 4d6 damage of the chromatic type selected (lightning, fire, acid, poison, or ice) of on a failed save, or half as much damage on a successful one. None of the Amulets of Draconic Wrath can be used again until after a short or long rest, and the same colored jewel cannot be used twice in succession.