The Orb of Vaermina is a glowing crystal orb in The Elder Scrolls IV: Oblivion that emits an unearthly sound. As its name suggests, the orb is a relic of the Daedric Prince Vaermina, stolen from its rightful place by the wizard, Arkved.
The wizard Arkved stole Vaermina's Orb. After offering a Black Soul Gem, Vaermina states that Arkved stole the orb from the dreams of her followers and pulled it into the waking world. Vaermina asks the Hero of Kvatch to retrieve it from Arkved's Tower. The Hero needs to fight leveled Daedra when going through the tower, until the Orb is finally found in Arkved's room at the end.
Returning the orb to Vaermina will please her, and she will give the Skull of Corruption as reward.
It is never stated what powers, if any, the orb possesses.