So I watched the latest episode of Uncle... why dinosaurs?
The spirits were angry at Takafumi's arrogant attitude by shorting the magic casting spells (when uncle lent him his power) so they cursed him by sending wind, adjusting the light, and transforming him for a moment.
Uncle who always polite to the spirits explained, "For the spirits that were introduced to you to the first time, if you arrogantly order them around -do it quickly-, you will get appropriate flashback."
The spirits of the wind disperse away.
The spirits of the light becomes too bright.
The spirits of formation changes his body into something else... the closest to the reptilian people on earth, borrowed from uncle's memory, it was Velociraptor from Mega Drive's version of Jurassic Park.
But uncle also thought that Takafumi would be lonely if it was just him alone so he copied his punishment transformation.
If they spend too much time transfomed they might not be able to pull it transformation back, just what like what's happened to uncle when he transformed into the flame dragon (thankfully Elf came to save him to transform back).
Takafumi did enjoy being a reptile since he doesn't have to think about future or anything at all, and that's why it's dangerous, uncle has to conviced him to turn back when they are in their reptile form.