AR alert: Percy Jackson
 

For those into book forms of AR, there is a new Percy Jackson book with several chapters of Teen to child AR (so far. Have not read the entire book yet)

*Spoilers ahead!*

In order to complete a new task set by the gods (or one in particular) Percy, Anabeth and Grover find themselves in the realm of Hebe, the goddess of youth in an arcade known as Hebe Jeebies. While trying to ascertain information, they end up angering the goddess, who causes all three of them to regress back to their 8 year old selves. Now, not only do they have to deal with her sacred animal, chickens, but the reemerging emotions that they once had as children while trying to find a way to change back.

No sense of transformation description, like when Percy was turned into a guinea pig. It's the stereotypical poof but thought it was worth mentioning.

Re: AR alert: Percy Jackson
 

So, small edit, but apparently this lasts for only several chapters. After managing to escape the chickens, Annabeth tricks Hebe into regressing back into a baby and then returning them and herself back to their original age (For Hebe, it is a teenager).Some slight process is shown as Percy watches Hebe regresses, but he doesn't go into too much detail.