Potion of dragon breath: when quaffed, it enables you to use the breath attacks of a specific type of dragon without being polymorphed into that dragon, either for a limited time or for a limited amount of uses or both.

The potion can be crafted by dipping any type of dragon scales in a potion of acid, which destroys the scales and turns the potion into dragon breath. It could be randomly generated, or never generate and rely on the player to make it.