Instrument

Rare Conjuration

When a non-bard tries to use the item, he/she rolls a d8: On a 2-7, nothing happens
On a 1 or 8: it deals 1d8 psychic and 4d8 lightning damage to the wielder.   If you're attuned (as bard) and you touch it, two floating disks (like those from floating disk spell) containing two sound-amplifiers spawn within 5 ft. from you.
You can use your bonus action to move both disks (within a range of 10ft. of you) mentally.
You can also rotate them to face your opponents.   The Rocc Bag of Thunder has 7 charges and regains 1d6 + 1 charges daily at dawn.
As an action, you can cast the thunderwave spell from the guitar spending at least 1 charge. The level of the spell equals the amount of charges you spend.
As action, you can spend 5 charges to use its Sound Wave ability. Sound Wave. Both amplifiers emit an huge soundwave (this ability has no effect on constructs or deafened creatures).
All creatures withing a 100-feet cone (starting from the disks) must make a DC (8 + your Charisma modifier) Constitution saving throw to take half of the 6d10 thunder damage and not be deafened for 24 hours or until their hearing is restored with a lesser restoration or better spell.

Cost: 5000gp
Weight: 7lbs