Age regression (ConceptClass, 3)
From Compile Worlds
Age regression is the concept in fantasy or sci-fi fiction of reducing a character's age, either physically, mentally, or both. Often, it is played for ironic laughs with characters who have an obsession with eternal youth, or often accompanies a Fountain of Youth trope set or episode in media.
In the Puyo series, age regression is Lagnus the Brave's gag and foil. He turns into a 10-year-old kid when he lacks the EXP necessary to Level up. This is played for laughs so Arle Nadja and Schezo Wegey can make fun of him. In Madou Monogatari (SEGA Saturn), however, Lagnus' curse is portrayed in a more sympathetic light, being the result of Yoggus sapping away Lagnus' power through Satan's Crystal Prison.
In Puyo Puyo 7, age regression (and it's opposite) are instead portrayed as a super-power that all the characters are capable of, gaining a significant advantage in a battle while in the younger/old states. Apparently, this was all the rage with the Primpian and Madou mages prior to the events of the game, because Henshin is the primary game mode.
Of course though, if you're Draco Centauros, then age regression magic is literally the worst possible thing you could ever do to a person. Not even torture of a poor shut-in mermaid compares to the grave sin that is turning Sig (and Schezo Wegey) into a baby. Perhaps this is a lesson for Accord to learn, as turning people into babies for your own amusement could have the awful consequences of having an angry dragon lady hold a grudge against you for several years. We can't possibly think of an individual who would actually enjoy this sort of thing happening to them all the same.