Unholy Fiddle

Magical item, artifact, requires attunement by a Bard, Legendary

An indestructible, tiny golden fiddle approximately the size of a keychain. It permanently smells of brimstone.

This item contains a maximum of 6 charges. Each time you finish a long rest, it regains 1d4 charges. The charges can be expended to modify the effects of any sound-based techniques in your kit.  

Amplify (2 Charges). Amplifies the effect of any spell or effect that has a single target by rolling double the normal amount of dice. For instance, if the spell normally deals 2d10, roll 4d10 instead.

Echo (2 Charges). Any sound-based spell or technique you use with this effect can now target up to three other creatures at the same time.

Cacophony (4 Charges). From your instrument, sound-omitting object, or band of demons, you unleash a sound so loud that it originates from that point as a shockwave audible out to a 20-mile radius. All Large-sized or smaller creatures within a 20-foot radius of you, including allies and yourself if the shockwave didn’t originate from you, must make a DC 20 Strength saving throw or be shoved 10 feet away from you by the shockwave, falling prone when you and/or they land. Additionally, any creatures within 60 feet of you, including you if the shockwave didn’t originate from you, must make a DC 16 Constitution saving throw. On a failure, they take 48 (10d8+8) Thunder damage become deaf for 1d4 days, or half as much on a success and not becoming deaf. An affected creature can repeat this saving throw at the end of its turns to end the deafness.