Vaermina is the Daedric Prince of Dreams, Nightmares and Evil Omens. She preys on sleeping mortals and can take their memorys and leave in their place horrifying images and events. She is one of the demonic daedra and is inherently evil.
 Plane of Oblivion
Her plane is called Quagmire and is a horrifying place which shifts from one terrifying event to another endlessy.
 Additional Information
Her Summoning Day is the 10th of Suns Height.
She is known to be allied with Sanguine.
Her Artifact is the Skull of Corruption and in previous games it produced a clone of whoever it was cast upon and it fought the original person. In Skyrim though it simply does 20 points of damage and 50 if powered with dreams from sleeping people.