Helm of the Chromatic Dragon

This iridescent helmet has been blessed by a powerful, evil dragon. While wearing this helmet, your breath weapon deals an extra 1d6 damage of its type, and you can choose whether it deals acid, cold, fire, lightning or poison damage. You can also choose if your breath weapon affects a 15-foot cone or 5-by-30-foot line, and if creatures affected by it must make a Dexterity or Constitution saving throw.

In addition, when you use your breath weapon, roll a d6. On a 5 or 6, you gain an additional use of your breath weapon before you need to finish a short or long rest.