You decide to change people physically and mentally. After all, where's the fun in going only halfway you think to yourself. Upon hearing your plan, Ceridwen flashes a wicked smile. "The purest change of all. What a sight it will be to behold." Nodding your head in agreement, you get out the notebook and inscribe your desired changes.
"On All Hallows Eve, all shall be changed into the costumes they don."
Satisfied, you put the pen and notebook aside. As you turn away from the notebook, Ceridwen read the inscription again, raising her eyebrows as she did so.
The following day was uneventful. You went about your affairs with minimal fuss. There were no telltale signals at school that anything was amiss. You couldn't stop thinking about the changes you had planned for the evening though. Who you were going to change. The scenes of chaos the changes would inspire. Endless thoughts circled and accumulated throughout the day just ready to be unleashed. Eventually, as early evening settled on the town, you collected your notebook and got ready to leave.
Heading downstairs, you remarked at the amount of effort your parents had put in to get the house in a Halloween spirit. Pumpkins, ghosts, decorations galore, your house had it all. As you walked down the hall, you passed your mother seeing off the first wave of trick or treaters. Not one to miss a beat, your mother was wearing a costumer of her own. "Horse?" you asked your mother.
"I wish hun. They were all out of that one, so I had to settle for the closest thing. Donkeys kind of look like horses anyway right?" your mother laughed as she headed towards the kitchen. "Here come and have one of my apples before you go. We can't have you filling up on candy all night long!" your mother said as she gave you a wink and nudge.
Not seeing anything wrong with having a quick snack, you followed behind your mother. You couldn't help but notice as you started chomping down on a caramel apple how good your mother's costume was. Evidently the costume shop she went to was very high quality. Distracted by the doorbell ringing, you excused yourself to go deal with the latest round of trick or treaters. The doorbell went off a few quick times in succession. "All right, all right! I'm coming!" you yell at the door, candy in hand. Opening the door, however, you are left with the sight of an empty porch. Looking around in confusion, you shrug your shoulders before heading back to finish your mother's treat.
Your mother smiled at you as you came back into the kitchen. "Trick, I guess" she laughed. You chuckled in agreement. Continuing to munch on your apple, you noticed an odd movement out of the corner of your eye. You could have sworn the tail hanging off your mother's costume just moved. Additionally, the flimsy donkey ears she had previously had on looked as though they had melded with her head. Neither tail nor ears looked like a cheap costume accessory anymore. A dinging from the front door broke you from your thoughts. "I've got it hun." your mother said. As she walked away, you could see the donkey tail positioned above your mother's shapely rear swishing excitedly.
Something was wrong. Your mother shouldn't be changing. You didn't write her name in the notebook. What was going on? Quickly pulling out the notebook, it was with shock that you noted you had inscribed that all wearers of costumes would change. "Oh no mom's going to change. Everyone's going to change. Got to fix this fast."
"Those kids sure had good costumes HAW." you heard your mother say as she re-entered the room. Glancing over at her, you noticed that her changes had progressed. In addition to her evident tail swishing behind her and tingling ears bouncing atop her head, you could now see a set of buck teeth imposing themselves on your mother's visage. "Gosh these caramel apples are so good! I could just eat these all night HAWWW!" At the latest outburst, your mother frowned and covered her mouth in embarrassment.
Recovering quickly, your mother quickly returned to the counter to collect another apple to chew on. As you got a closer look at her, you were shocked to see your mother's sizeable breasts shrinking into her chest. The left one went first, shuddering and pulsating as it faded from view with the right quickly following. Wait that wasn't right. Why would your mother's breasts be fading? Oh no, you thought to yourself. "Uh mom, was that a girl's donkey costume you got?"
"Can't say I know hunHAAWWW. It was the first and only one I could find HAWWW." your mother replied, coughing as she tried to settle the brays. Your mother's coughing gave you a great view of her now very flat and masculine chest. On closer inspection, you could also see that the costume your mother had been wearing had melded with her body. Her skin now appeared to be covered in small, grey hairs. "You know what HAAWWW. I feel a bit strange hun HAWWW. Do you feel... oh my." Your mother's face went beet red as her tail lifted and several turds fell from her behind.
"Oh my god, what is happening to me HAAWWW! Please help son!" your mother cried as she finally took notice of her changes. You quickly scrambled to get the notebook out to try to fix your mother, her brays and cries for help filling the room. You were distracted from your search by a frantic cry from your mother. "Nothing's coming out. Why isn't anything coming out. I need to go so bad! Ugh" your mom hunched over, obviously trying to further relieve herself.
Low groans and brays could be heard from the woman as she turned away from your prying eyes. "Gotta go so bad... so sorry son." your mother mumbled as she squatted, her back turn turned to you. Forgetting the notebook for a second, you moved towards your mother, worried she may be really unwell. As you got closer, the sound of liquid hitting the kitchen tiles began to resound around the room. Trying to get your mother to the bathroom, you offer her your arm to help her to her feet. You were met with a startling sight as the woman turned towards you.
A long and growing donkey cock hung lazily from your mother's crotch, urine spraying from it onto the floor. Your mother's face, flushed with embarrassment from her predicament, became even redder as her new body involuntarily began pushing against something. With a resounding groan, a testicle dropped from your mother's crotch below her new equipment. A second groan and bray escaped her as a second fell alongside it. With a last dribble your mother finished relieving herself. With a look of shock, the woman reached towards her new appendage. Upon brushing the testicles and cock, a sharp exhale escaped from the woman followed by a groan. "Oh hun, please help me HAAWWWWWW." your mother began braying uncontrollably.
The woman, to this stage still very much mentally herself, was clearly being assaulted by the new male hormones produced by her new equipment. You could only watch as the drooping testicles swelled with seed. The previously drooping cock quickly rocketed to full attention. Your mother began clutching at her face, the donkey trying to take control. "My mind hun. It's trying to take my minHAAWWWW!" Formerly dainty hands and feet merged together, forming a hard substance. Before long, your mother was clutching her face with hooves. Former hands falling away from her face, you could see the donkey quickly winning the fight with the woman. Stumbling back and forth, your mother's cock began leaking onto the surrounding floor. Eventually, having fully descending into a state of uncontrollable lust, the former woman charged at you.
You scrambled away as best you could. Dodging your mother as she attacked you, desperate to pin you down. "HunHAWW, pleasHAAWW, help meHAAWW". You sprinted for the door, the former mother in hot pursuit. Trying to wrench the front door open, you were quickly crushed against it, your mother's needy spear sticking into your belly. Looking your mother straight in the eyes, you saw the last of her human intellect fade as her visage stretched out into a muzzle. "HoonneeeeyyyHAW!" You threw the door open and tumbled out as your mother's new body bucked in a state of pure madness. Hot cum sprayed from the beast's shaft, drenching the door and surrounding entrance portal. Not done by any stretch, the beast that had been your mother raced past you into the early evening, desperate to satisfy her urges to mate.
You were only able to get your bearings briefly as you became aware of the world you had stumble out into. "Well that was exciting!" Ceridwen exclaimed as she stepped up beside you. "What's next?"