Theriomorphosis Potion is one of the magical potions described in Monster Girl Encyclopedia World Guide III: Sabbath Grimoire.
Guide Book Entry[edit]
A reddish-brown colored liquid medicine that always has a faint heat. It is a potion made from the research of the mana possessed by animals and Mamono Realm Beasts, and when human men drink it, it is possible to temporarily turn their bodies into "beasts". Although they are unconditionally called "Theriomorphosis Potions", there are many kinds of potion that change men into different beasts, and because the use for this potion is for the enjoyment of wild sex being raped by the husband who became a beast himself with literal animal lust, those that turn them into large and powerful beasts such as wolves and horses are preferred.
By drinking a whole dose, they transform into a complete "beast" with four legs, and by drinking half, the whole body is covered in body hair, and it is also possible to change into the form of a "beastman" that can walk on two legs like a human while having the head of a beast. Along with the increase in physical abilities, men who have become beasts accordingly have their senses of sight, hearing, and smell rapidly increased, which will make them feel well attuned to being a "male". On the other hand, as a consequence of being a beast, mental aptitude drops significantly, and if there is an invitation for a male in front of them, they cannot resist. If that happens, they will only be able to think in the spirit of a beast to mate in order to conceive a child, and the male will try to pounce and earnestly thrust their hips.
Furthermore, the men that have become beasts will give off a unique "beast scent". It is a smell also said to be a beast stench, but to monsters, it is like the concentrated body odor of men, and with just a sniff the inside of the head becomes dizzy, and the womb begins to throb and ache. In addition, the semen released by men that have become beasts also contains beast scent, and the feeling of the smell sticking to your insides when it is released satisfies the desire to be dominated by the instinct of males, and seems to become a habit.
Like the "Tentacle Potion", because it is made as a potion intended for men, powerful effects do not appear for both human women and monsters. Even if a human woman should drink it, almost no change can be seen from simply drinking it, but this magical potion stimulates the "beast's instinct" that dwells within women, and in some cases may awaken it. For example, in the case of being looked at with eyes full of animal desire from a partner recognized as a male, that is, a man they hold feelings for, at that moment the inside of the body suddenly becomes hot, shivers, and is stricken with a sense of both fear and expectation. Also, if there is something like a swollen penis before their eyes, due to the throbbing instinct of a beast, heat swiftly spreads throughout the body, along with losing their strength and being caught in place, becoming completely unable to take their eyes off of the penis that is a symbol of a male. If that happens, while breathing roughly like a beast, they will fixedly stare at the thrusting penis, and wait spread out until the male comes to mount them.
Also, this magical potion can boost one's aptitude for "Theriomancy", increasing the power of all magicks belonging to it. In addition, when a human woman repeatedly drinks this potion, it continuously stimulates the instinct of a beast, the qualities of a beast increase, and each time they drink it it becomes easier to get caught up in "Howling Force", along with beginning to show extremely high qualities to monsterize into races classified as beastmen.