"Wizardry II: The Knight of Diamonds is the second scenario in the Wizardry series of computer role-playing games. It was published in 1982 by Sir-tech Software, Inc.
The game begins with the city of Llylgamyn under siege. Llylgamyn's rulers have been killed, and the city's only hope is for the recovery of the staff of Gnilda, only obtainable from trading the mystic "Knight of Diamonds" armor from the legendary Knight of Diamonds to fend off the invaders."
Source: Wikipedia, "Wizardry_II:_The_Knight_of_Diamonds," available under the CC-BY-SA License.