Horn of Valhalla, Iron

You can take a Magic action to blow this horn. In response, warrior spirits from the plane of Ysgard appear in unoccupied spaces within 60 feet of you. Each spirit uses the Berserker stat block and returns to Ysgard after 1 hour or when it drops to 0 Hit Points. The spirits look like living, breathing warriors, and they have Immunity to the Charmed and Frightened conditions. Once you use the horn, it can't be used again until 7 days have passed.

A iron horn summons 5 Berserkers. To use the iron horn, you must have Proficiency with all Martial weapons.

If you blow the horn without meeting its requirement, the summoned Berserkers attack you. If you meet the requirement, they are Friendly [Attitude] to you and your allies and follow your commands.