I was looking around the archives and noticed how adventurers were a common occurrence and noticed that most transformations caused by monsters involve contact with the creature and/or it's cum/body fluids. So I came up with this idea.

Libidonics:

Libidonics is an ancient and, in the modern realm obscure, martial art form created by merging the ideas of the body and spirit with the mana energy in the air to create an effect similar to magic. This being said, the biggest difference between this practice and actual magic is the severe limitation to what can be done with the mana. The word Libidonics is actually a compound of the core concepts of the art form, and can be broken down into three separate parts: "Libi" "do" and "nics".

The first part, "libi", is a shortened form of 'libido'. This pertains to the idea that one can channel more mana if one has a larger libido, and also a larger threshold to how much pleasure one can endure before cumming. It also stems from the earliest practice of channeling mana into ones dick to actually increase the duration of the act and heighten the pleasure gained. It is believed that the martial art was started by a student who was the laughing stock of his school due to cumming early.

The second part, "do" stand for 'double', noting the balance of body and spirit needed to perform this art. The 'body' refers to the overall fitness of the practitioner, while the 'spirit' refers to his or her mental clarity and perceptive ability.

The final part, "nics", is an ancient word meaning 'channel'. This not only refers the the practice of drawing mana from the air and utilizing it, but also the idea of channeling motion and force. Unlike many other combat forms, attacks from this art use not only the practitioners force, but also the force of his opponent.

Mana channeling in Libidonics is similar, but also vastly different than magic. Instead of incantations and runes, a libidist (as practitioners are called) draws mana out of the air and shapes it by will alone. Not only does this require a lot of discipline, but the libidist is limited to what he can do with the power. Overall, there are six ways to utilize the power:
-Boost: the libidist uses the power to enhance his strength, speed, senses, or endurance.
-Guard: the libidist creates a barrier around him that lessens harm to hum/her.
-Push: the libidist actually compresses the mana into a form of energy and shoots it.
-Sustain: the libidist uses the energy to file his body without the need for food.
-Heal: the libidist uses the power to make cells repair themselves quicker.
-Charge: the libidist channels the energy through limbs and objects to surround them in energy.

Of this art form, there are also two subdivisions: bracers, who fight without weapons; and reachers, who use weapons. The names originated form the original weapons used by practitioners. While reachers can be found using almost any weapon, most use reach weapons like chains or ropes. It makes sense since reachers originally created this form to combat beasts with infective transformation abilities and mages who used spells from a distance. One of the most common weapons used by reachers is a chain with a hook on the end, though those who do not wish to kill will frequently use lassos instead.

While no formal schools of this art currently exist, libidists will happily train anyone interested in the art. Nomads by nature, they freely wander the land in search of work as hunters or fighters; taking disciples if they deem someone worthy. Some even offer to teach sections of it in addition to sex courses, and many lessons often turn into orgies of some sort.
Few practitioners are transformed, but no formal rule against it exists. Those that are see their transformations as extensions of the self, and those with animal features view it as a representation of becoming closer to nature.