D&D 5th: Demon Tower of Madness
Horn of Blasting
Old Cracked Bone Horn
This plain brass horn is badly dented, but despite the apparent damage, it is fully functional. A horn of blasting functions as a normal trumpet unless someone speaks the command word and then blows the horn. Even without the command word, the horn emits a deep, roaring rumble when blown. The blast causes the ground in front of the horn to quake slightly, and dust kicks into the air as if disturbed by a sudden gale.
As an action, you speak the horn’s command word and then blow the horn. It emits a thunderous blast in a 30-‐foot cone. Each creature in the cone must make a DC 14 Constitution saving throw. On a failed save, a creature takes 5d6 thunder damage, and it is deafened for 1 minute. On a successful save, a creature takes half as much damage and is not deafened. Crystalline creatures and objects have disadvantage on the saving throw and take 7d6 damage instead of 5d6.
Each use of the horn’s magic beyond the first during a single day has a 20 percent cumulative chance of causing the horn to explode. The explosion deals 10d6 thunder damage to the blower and destroys the horn.