Katie was your average runner with a fit body, small b-cup breasts, and a decent ass. But still very attractive with a pretty face and blonde hair that reached a little past shoulder length put up in a ponytail.
She was walking through the mall wearing a comfortable top and yoga pants that showed off her ass, when she spotted a store that she had never seen before called "The Magic Shop." Her curiosity got the better of her and she went inside. The store looked a lot bigger on the inside with rows full of random objects. There was an old man sitting at the desk right beside her, as she walked in he greeted her, "Hello there young lady welcome to the magic shop what can i help you with." Katie thought about it and asked, "Is there anything you have that could make me run faster?"
"Right this way." the old man said as he came around the desk and started walking down one of the isles. Katie followed him not knowing what to expect. The old man stopped walking and scanned the shelves "aha" the old man exclaimed. He reached up and grabbed a wooden box, as he opened it Katie could see it was filled with vials that had strange symbols on them, but some had pictures as well.
The old man took two vials out of the box and handed them to Katie. One had a picture of a stallion on it, an the other only had the strange symbols. " The vial with the stallion on it will make you run faster and the other vial is a bonus, but only take one drop of the vial with the stallion on it" the old man said."how much are they?" Katie asked. "Oh they are free young lady everything in this store is" the old man said. Katie didnt believe that these magic vials would do anything, but who could argue with free stuff. She thanked the old man and walked out of the store thinking of what an odd store that was where everything is free, maybe they were going out of business.
When Katie got home she thought she might as well try the vials, what could be the harm. She looked at the vials and decided to try the one that had no picture first. She took the top off and drank it, it had a sweet taste almost like milk. She then felt a tightness in her bra. She wondered why her bra was so tight when she noticed that it was because her boobs were growing. As her boobs continued to grow Katie began to not be able to breath as her tiny bra constricted her chest. She quickly struggled to unhook her bra before it suffocated her. She unclasped it letting her growing breasts pop free of their restraints. Her boobs continued to grow until they were almost to big to be DDs ripping her shirt in the process when they stopped growing. Katie couldn't believe her eyes, the vial really worked. She was happy, she had always wanted bigger breasts and now she had some of the biggest boobs she had ever seen. Katie was excited now to try her other vial knowing that it would make her run faster.
She took the vial with the stallion on it and remembered what the old man had said so she only drank one drop. She waited and nothing happened so despite the old man warning her she drank a quarter of the vial. She then felt a heat and tingling sensation all through out her crotch and on her tailbone. She felt a pinch on her tailbone as her tail grew, growing into a full blonde horses tail. She then felt pressure as her butt expanded and grew into a ginormous slappable ass tearing her yoga pants and panties to shreds. Katie was shocked at what was happening to her as she looked at her huge ass and tail, and the tattered remains of her cloths around her feet. The heat and the tingling in her crotch increased. She then felt like a bitch in heat as an immense pleasure swept over her. Her anus felt hot as it began to change, it puffed out and expanded into a stallions ass. Then her pussy grew hot and Katie felt a pressure inside her as her organs rearranged. She tried to satisfy her lust by fingering herself but was heartbroken to find her pussy lips had grown together. Her clit began to grow, rapidly transforming. Katie was horrified as she watched her huge horsecock grow out of what used to be her pussy. As her beast of a cock grew, a pair of coconut sized balls dropped into her formed sack. Katie couldn't take the state of lust she was in, she needed to pleasure herself, so she began to slip her hand between her enormous, slappable cheeks to finger her puffed, throbbing horse ass. There was a churning in her huge balls as her horsecock reached its peak at 2.6ft, a cock truly fit for a stallion. Katie moaned as she continued to hungrily finger her ass with one hand she moved her other hand to stroke her monster horsecock. Something began rising up her shaft begging for an escape. Katie screamed as cum exploded out of her horsecock gushing everywhere, rocking her whole body with the biggest orgasm of her life. After what seemed like an eternity her orgasm died down and her cock began to slither its way back into its sheath. Katie had no words to describe what had just happened to her but she was sure about one thing, all these new changes certainly were not going to make her run faster.
Katie went to the bathroom to asses the damage. She looked at her new cum covered body in the mirror, she had huge DD tits, A gargantuan ass with a long blonds horse tail above it along with a puffy black horse anus, and of course her huge black and pink mottled stallions cock equipt with coconut sized balls hanging below. She knew the truth but had to be sure about it, she lifted up her balls and sure enough her pussy was gone. Even though it was terrible Katie thought she kind of looked sexy with her new additions. Katie had no clue what to do next but she did wonder what would happen if she drank the rest of the stallion vial.