@Mistresstopia

In the lore of the Mistresstopia comic book series. slaves come from a couple of primary source

In this female-supremacist society, men from the mundane world are relegated to servitude and sold globally through the empire's marketplace.

The evil Teru possesses ancient, powerful dark telepathy. He uses specialized slave chant spells to infiltrate a target's mind, stripping away their free will and trapping them in a state of mental submission. This mind manipulation allowed him to easily break the spirits of captured fighters and force them into servitude.

Teru partnered directly with Sovereign Sanura and Mistress Armina to manifest the foundations of Mistresstopia. While Armina and the Femme Order use artifacts like the "S-Ring" to physically summon and harvest elemental beasts from the pockets of the Unknown Universe, Teru’s dark magic and technology provided the infrastructure required to pacify, bind, and structurally format these ethereal entities into specialized combat thralls.