Horn of the Fallen

Wondrous item, rare (requires attunement by a Fighter)
This ancient, weathered war horn bears the markings of countless battles and is said to be imbued with the spirits of warriors long gone. When blown, it invokes the courage and physical aid of these fallen heroes.
Activation: As an action, you can blow the Horn of the Fallen, expending a charge. It has 3 charges and regains all expended charges at dawn.
Special Abilities:
# Call to Valor: When you blow the horn, a spectral battalion of warrior spirits manifests around you. These spectral warriors resemble warriors from various eras, each wielding a different weapon, and they stand at the ready to aid you in battle.
# Spiritual Inspiration: While the spectral warriors are present, you and your allies gain temporary hit points equal to your Fighter level + your Charisma modifier. These temporary hit points last for 1 minute.
# Echoes of the Past: The spectral warriors fight alongside you in combat. They have the following statistics:
#* AC: 15
#* Hit Points: 20 (4d8)
#* Speed: 30 ft.
#* Attack: Melee Weapon Attack, +6 to hit, reach 5 ft., one target. Hit: 8 (1d8 + 4) slashing damage.
#* Special Ability: The spectral warriors have advantage on saving throws against being frightened and resistance to fear effects.
# Lasting Valor: The spectral warriors remain in combat for 1 minute or until all charges are expended. Afterward, they fade away, returning to the ethereal plane. You cannot use the Horn of the Fallen again until the next dawn.