Band of bloodlust

The whispers of violence speak to you, they ring in your ears with a pleasant melody. You desire to use the magic and power of music to make every strike sing with the song of brutality to quench your unquenchable bloodlust. These gifts are, perhaps ironically, ingrained in your blood, a part of you since birth. Perhaps released when you began using magic. Use your magical ability to inspire others to instead share your bloodlust willingly, or maybe whether they like it or not. Depending on the hands this gift are placed in, it may be a curse, or worse, a gift.

Satisfaction in death

You may expend a use of bardic inspiration to gain temporary hp equal to your bardic inspiration die+your bard level, while you have these temporary hit points your desperation for violence reaches new levels, granting you additional abilities. 

3rd level: Whenever you roll for damage, you may add your charisma modifier to the total.

5th level: Whenever an ally makes an attack roll expending your bardic inspiration, their crit range goes down by 1, so if they would normally crit on a 20, they now would on a 19

7th level: When a creature within 30 feet of you makes an attack roll you may use your reaction to allow them to make an additional attack roll against a different creature within their range, dealing damage equal to the maximum value of your bardic inspiration die

10th level: When you activate satisfaction in death, you may add an additional d8 + con to the temporary hit points, additionally you may expend hit die up to your proficiency bonus and add them to the roll.

15th level: When a creature within 60 ft of you expends your bardic inspiration die on an attack roll, roll your bardic inspiration die, if it is 6 or above it is not expended.

18th level:When an ally within 30 ft of you expends their bardic inspiration on an attack and it is not recovered, you and the creature gain temporary hit points equal to a roll of your bardic inspiration dice, these temporary hit points add to your satisfaction in death temporary hit points.

Inspired bloodlust

Whenever an ally uses one of your bardic inspiration die, they may add an additional die equal to your bardic inspiration dice to the damage roll.

Instill bloodlust

Expending a use of your bardic inspiration, you may force another creature to make a charisma saving throw, on a fail, a lust for blood overcomes them and they must make an attack against a creature within their melee range, if their are multiple creatures in range, they attack one at random. 

Inspired by blood

When a creature within 30 ft of you is reduced to 0 hit points, you may expend a hit die to regain a use of bardic inspiration.

Desperation in inspiration

When you or a creature that has an unspent use of inspiration makes an attack action, they may expend their bardic inspiration to make an additional attack, adding your charisma modifier to the damage. After they make the attack they take 1d12 psychic damage, a penance for over exerting themselves.