The "Raging Bull" was a name given to a captive minotaur in the Lower Heart ward of Skullport in Undermountain, held in a cage suspended from the cavern ceiling, high above the street just outside the doors of The Deepfires inn.
Sometime in the 1340s DR, an unknown slaver imprisoned the minotaur in the almost unbreakable cage and abandoned him there. The minotaur had a ring of sustenance to nourish him, but this only worked for seven days and took seven days to recharge, leaving the minotaur to starve in this time.
He was still there by 1370 DR, now hopelessly insane. He assaulted anyone who risked coming close to his cage, even to try to free him. He was also tormented by cruel folk like Quinan Vamaed, who saw this unending torture as a gift to the goddess Loviatar.
Known as the Raging Bull, the minotaur had become a notorious local landmark in Skullport. His angry bellows echoed across Skullport on a disturbingly regular basis, and one could follow them to find The Deepfires inn. However, his dung fell on the street below.
Conmen often tried to sell the Raging Bull as a prized slave to people new to Skullport, prompting a common local saying: "If you believe that, I've got a minotaur to sell you."