In modern times, it is the umbrella term for the hundreds of different laws, made by both magical and non-magical governments and organizations, that explicity forbid using magic on Humanoid biology.
In the early ages of magic, almost as soon as the field of biomancy itself emerged, wizards began to experiment on other living creatures and even themselves to satisfy their curiosity, and sometimes for the purposes of sadistic pleasure.
Immediately realizing the potential for biomancy conducted on humans to be dangerous and potentially, heavily abused, many early wizarding communities made pacts and oaths to never practice magic on Humans unless it was for the purposes of healing. This was done to both protect themselves from other wizards by making a 'gentlemen's agreement' to not use dark magic in battle, and to improve the reputation of wizards as seen by non-magical people. Many wizarding communities and guilds insisted that initiates swear against 'cursing Human flesh' as part of their initiation, and ejected, exiled or executed members caught doing so.
Human biomancy quickly became regarded as a form of Dark magic. Even when punishing those found to be guilty of it, wizards refrained from practicing it themselves and preferred to simply behead or hang offenders.
Despite this, violations of what was now known as the 'Flesh Taboo' by rogue wizards heightened fears of magic. They were a contributing factor to anti-magical prejudice and persecution of wizards by non-magical people and the Catholic Church in the later centuries, most notably during the Crusades and the Spanish Inquisition.
The Knights Illuminor was originally a Christian anti-magic organization formed with the intent of exterminating creations resulting from biomancy, especially Human biomancy. This was one of their core tenets, and persists even to the modern day as Illuminors are sworn to kill anyone they find violating the Taboo.
Throughout Medieval to Renaissance ages, there have been examples of famous wizards that violated the Flesh Taboo.
- 13th century: Lycanthropy was made by an unknown Wizard, causing humans to transform into a feral wolf/man hybrid, known as werewolves and go onto a killing spree until dawn or sunrise where they revert back to normal with no memory of what happened after the transformation.
- 15th century: Biomancy was in its infancy and practiced in less effective, limited forms due to lack of scientific knowledge regarding biology. Nevertheless there were a few examples of the taboo being broken that were famous.
- 16th century:
- An unknown wizard in Western Europe became notorious for experimenting on Human subjects before his work was denounced as dark matter, and was chased and exiled from Europe, escaping to Australia to continue his work after transforming himself into a humanoid with animalistic traits of a wolf. He eventually succeeded in creating a humanoid species that could reproduce, the Anthro-feralis. This is arguably the most successful violation of the flesh taboo, as Anthros became a species that ended up dominating to Australia and even beginning to explore and expand beyond their native range by the time of their discovery.
- 18th century:
- Victor Frankenstein was a biomancer scientist attempting to find a way to reanimate dead tissue and to prolong or even indefinitely extend life. His experiments were semi-successful but resulted in his own untimely death.