Visionaries Knights of the Magical Light (1987)

Reekon and Mortdred come across the lost city of Khemir where all labor was done by robot slaves. Now that the Age of Technology is over there are no robot slaves left to do their bidding. Darkstorm promises new human slaves to the Khemirites if they swear loyalty to him. So, the Darkling Lords and the Khemirites set up a trap on New Valerik, and capture the Spectral Knights to make them slaves.