Horn of Valhalla

Horn of Valhalla is a wondrous item that has the power to summon forth the spirits of barbarians from their afterlife to fight for the summoner. The horns come in four different types which appear to be normal horns until the command word is spoken.
 * Silver, which can summon 4 to 10 barbarians.
 * Brass, which can summon 3 to 9 barbarians.
 * Bronze, which can summon 2 to 8 barbarians.
 * Iron, which can summon 2 to 5 barbarians.

In the Forgotten Realms Campaign setting this magic item could correctly be named Horn of Warrior's Rest.