Think theres a bug. Beat Zone one 3 times now on Hard, exit portal never appears. third attempt sat there for 5 min listening to the music loop and no portal appeared.
Lake serpent or the flame drake? I’m guessing serpent since something seems to be borked about him. I know the flame drake works so in the meantime I would try starting a new game and make sure you get the little boss on the map. Restart game until he shows up since its a 50/50 chance until I get it fixed.