Divine Academy
If it turned out to be a real siren singing the song, I would be able to command it to stop; the siren would be unable to disobey me due to my command over all sea creatures.
Whereas the first floor of the prison was empty, the second floor was at maximum capacity. It was full of Hydras, Krakens, and Sirens with higher magic levels. The Hydra seems to have been locked in the prison for a while, as I was able to walk by it without it so much as lifting one of its nine heads. The Krakens kept reaching between their cell doors, trying to wrap one of their dangerous tentacles around me and drain me of my divine powers; unfortunately for them, I'd learned all about their magical attributes growin