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, she states that Arkved stole the orb from the dreams of her followers and pulled it into the waking world. Vaermina asks the Hero to retrieve it from his Arkved's Tower. They need 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.
During the events of The Elder Scrolls: Legends it is revealed that the Orb of Vaermina can be used to spy on locations.