I have a lvl 14 College of Swords Bard. He plays war drums. What would be spells for a Legendary War Drum - Instruments of the Bards.

The instruments for reference: https://aversten.obsidianportal.com/wiki_pages/instrument-of-the-bards.

I don't see any particular theme for the spells on those so I really don't know what to pick for a war drum.

Thunderclap, Earth Tremor, Thunder Step, Shatter, Thunderwave, Deafness?

Symbol caught my attention. Perhaps it could be adjusted somehow for 60ft or 120ft (something to capture the idea 'of within earshot'). And limited to Fear, Hopelessness, and Insanity. Looking at it I guess it probably couldn't have a 1 min casting time if the idea is playing war drums to intimidate the enemy. I've never homebrewed spell, I wouldn't know how to balance things.

Otto’s Irresistible Dance, Spirit Guardians, Enthrall.... There is also a now abandoned old UA spell called: 

Unearthly Chorus

LEVEL

1st

CASTING TIME

1 Action

RANGE/AREA

Self (30 ft )

COMPONENTS

V

DURATION

Concentration 10 Minutes

SCHOOL

Illusion

ATTACK/SAVE

CHA Save

DAMAGE/EFFECT

Buff (...)

 

Music of a style you choose fills the air around you in a 30-foot radius. The music spreads around corners and can be heard from up to 100 feet away. The music moves with you, centered on you for the duration.

Until the spell ends, you make Charisma (Performance) checks with advantage. In addition, you can use a bonus action on each of your turns to beguile one creature you choose within 30 feet of you that can see you and hear the music. The creature must make a Charisma saving throw. If you or your companions are attacking it, the creature automatically succeeds on the saving throw. On a failure, the creature becomes friendly to you for as long as it can hear the music and for 1 hour thereafter. You make Charisma (Deception) checks and Charisma (Persuasion) checks against creatures made friendly by this spell with advantage.