Jaws clenched, wracked by waves and waves of magic, you can hardly think straight. All you can feel are tingles hitting your body all over. The transformations are so little and numerous that your brain barely registers them. Your vision feels blurry and you close your eyes. You did not expect this at all. You had thought a puff of smoke would appear in front of you, all to reveal a great beauty in front of you. Instead, you sense your chest expand - nay, balloon up. Your butt also blows up and your bones elongate, followed by your muscles, skin and tendons. Your bones especially become slender at the level of your hands and feet. Your organs shift, twist and shrink, rather uncomfortably. The worst of the weird occurs between your legs. You are aware of two lumps of flesh making their way inexorably upwards in your pelvis after a strange bigger thing like a slug dug into your flesh as if it was mere clay. The two lumps of flesh settle on each side of your groin, settling there, while the opening of this new organ expands and enlarges. This horrible part of your transformation - if rather painless - diverts your mind from the dull pains of your nose clinching - indeed like your waist - along with your eyes widening and lips fatten up as if you'd taken up a truckload of fillers in there.
As you finally get your balance back, you notice that you take more time to regain said balance. Why are your shores too big and uncomfortable? Why are your clothes too loose? Why does your body feel so foreign? Yet right after your eyes adjust again to the world around you, you see what you had asked for. Finally! A gorgeous blonde bombshells with the right proportions. All the right proportions. To die for! Those lips! She must have massive titties too! Underneath those clothes. Clothes... Clothes that are like yours... That are yours... You see easily now that you are staring at a mirror. This girl in your clothes... is yourself! You scream, a high-pitched shout that resonates in the forest. Oh no! The wish interpreted your wish and its wording completely wrong! You have to change this! It's a catastrophe! Worse, you stare at your new boobs and down and see things that horrify you. You would not mind them on an actual girl but on you... Gross! You have to toss a coin and redo that wish fast!
But that is when you see that the well is gone, replaced by a big stole monolith. The forest is unknown to you, much thicker than before! Where are you? You can't stay here like that because of a stupid wish!
Little do you know that you are in a land of myths, legends and tales now, and that woods are rife with creatures that would be delighted to grab you... In fact, you can see bushes rustling and you get away, hoping against hope that whatever is coming in your direction will just be interested in the mirror...