La puerta de Ptolomeo (Bartimeo 3)

The magic feels so integral to the story but also quite unique. I'm curious whether the rules were planned from the start or evolved during writing.

His decisions often kept me guessing if he was doing the right thing or just acting impulsively. What reactions did others have to his actions?

The world feels so vivid and layered. I wonder if the author based it on a real place or created it entirely from imagination.