Silver Horn of Valhalla is an item in Baldur's Gate II: Shadows of Amn. For 2,000 and a diamond, Maheer the Storekeep in the Waukeen's Promenade can upgrade the Silver Horn into a Bronze Horn of Valhalla.
It can summon a 5th level warrior once per day for 1 turn.
|“||In the halls of Valhalla rest the most valiant of warriors. Their service to war during their lives has rewarded them with honored positions in Valhalla. As part of their service, these warriors must offer their service to any who blow a horn of Valhalla. This horn will summon forth a 5th-level berserk warrior who will fight for the summoner for 1 turn. The horn may be used once per day.||”|