Amy: "Ok if I have to transform more I don't really want to become something that isn't human like, would a fairy work?"
Old man: "Sure, but that particular collar doesn't grant magic powers in case you had any ideas"
Lina: "Here goes nothing then. I commend Amy to become a fairy, she will keep everything in mind, personality, and spirit as it is now but as a fairy with monarch like wings and light blue hair. She would also stay the same size as she is right now."
Just then the collar glowed, then slowly Amy's hair slowly transitioned from the scalp out to a blue color like the daytime sky, her ears came out to a point like an elf. The enchantment modified her clothing to allow for wings that came in with a glowing pattern before materializing into a big stunning pair of monarch wings complete with deep orange and black patterns. Suddenly the leash loosened it's grip on Lina and fell to the floor.
Old man: "Now that's set I'll go fetch the antidote"
The old man walked away down an aisle and returned with a white leash collar set.
Old man: "This needs to be worn in the same direction as you worn the black set, it reverses any changes made by similar differently colored sets I sell. I'll give this one to you two for free since it was my fault I let you leave without properly ensuring you knew how the item was to be used. You may use the effects of the black and white collars as much as you'd like however mental and personality changes, the more dramatic, are harder to reverse so keep that in mind"
The two thanked the Old man and left the store.