Clothing/Defense/Ornament/Stone of Breath Absorption
very rare
This item is immune to damage from the breath weapons of all dragons. When it is exposed to the breath weapon of any true dragon, instead of taking damage, it absorbs the energy of the dragon's breath and stores it for later use. (This in no way affects the damage that other creatures take from the breath weapon, even the item's holder.) While the item is charged in this way, you can use an action to call forth the breath contained within. The item expends all of its power to unleash a breath weapon with the same size, shape, damage type, damage dice, and saving throw as the breath that it absorbed. Once used in this way, it cannot be charged again until the next dawn. The item can hold only one charge at a time.
Chromatic dragons will sometimes gift these as gems to their most prized followers as a token of power, and to help spread fear and carnage. The Draconic Order appears to have a number of these items that they use during combat with the Cult of the Wyrm, though it is not clear if the Order knows how to create them, if they have a horde of them they safeguard, or if they are getting them from someplace else.