Wondrous Item, rare
A magical horn imbued with an unstable enchantment replicating a white dragon's breath.
Using an action you can expend this horn's singular charge, casting the Cone of Cold (DC 15) spell from the horn. After the charge is used roll a d20. On a roll of 1 the horn cracks and the enchantment is lost. An uncracked horn regains it's expended charge at the end of a long rest.