The human body contains mana, the life force that can be used for use as a source for magic. The individual's capacity for mana slowly grows with time as the person ages into adulthood, finally reaching its limits during middle age, and then steadily declines. This serves as the basis for magecraft, the study of combining magic with science to advance both fields. A mage can substitute the mana of others for a magical source with no cost to themselves, transferring all the risk to the victim and leaving their own mana intact for use in less risky endeavors. Within each male sperm cell is a microscopic organism known as animalcule, a complete preformed individual representing miniature versions of human beings. These preformed humans develop and enlarge into fully formed human beings through the process of conception and birth. Magecraft allows individuals to bypass this long and convoluted process to create life in order to create a perfect servant loyal to its creator, known as a homunculus. These homunculi are grown within a specially built cauldron designed to hold magic brews. This brew is filled with various ingredients, such as eye of newt, as well as other lay ingredients, such as cow intestines, followed by magical words of power known as incantations. The most important is the sperm of the male containing the animalcule, which are produced by the millions within semen at one time. These various miniatures combine within the brew to create one single being. The resulting "child" emerges from this concoction as a fully grown adult, bound to obey its master's commands.
These homunculi must be continuously powered by a magical power source taking the form of a philosopher's stone, an item created from the soul of a human being. This gives the creature life and the ability to perform its tasks. Although they are intelligent, homunculi lack free will and individuality, making them the perfect servant to obey their master's commands. The one drawback of this creation process is that the resulting ritual damages the reproductive capabilities of the wizard, preventing him from having any future children or creating more homunculi. However, recent technological advances have allowed one to bypass this inconvenience. Cryomancy is a form of magecraft involving the study of creating low temperatures as well as their effects. This allows for the deep freezing and preservation of materials so they can be used in the far future. Sperm freezing is a revolutionary reproductive technology that provides a way for individuals to cryogenically preserve and store their seed within sperm banks, giving prospective parents various options. Technology has improved to the point where these banks can be small, compact, and consumer friendly, doing away with the large buildings and storage facilities of the past.
This can also be used to overcome the limiting capacity of homunculi. A wizard can simply store animalcules within these compact chambers and preserve them with a spell to be thawed out at a later date to create more creatures. This would allow for individuals to build their own private armies of homunculi within their own personally owned facilities whenever they so choose. As it is the most convenient option, many wizards would do this of their own accord in secret to go to war against others, creating a world where mages do battle with each other through their powerful servants.
How can mages be prevented from building their own armies of homunculi?