Castle Karstaag is a castle found in The Elder Scrolls III: Bloodmoon. It can be found in the Moesring Mountains region, west of Skaal Village. The Nerevarine enters this castle during the quests "The Castle Karstaag" and "Siege of Castle Karstaag." It is owned by Karstaag, a Frost Giant, but Karstaag has been taken away by werewolves. In his absence, Dulk and his Rieklings, as well as several Grahls, have taken over the castle.