huh, I had tried that before with the dragon, lamia, and salamander forms and nothing happened... Not sure why it worked now. Maybe you have to beat the dragons demon first? Any way, ability description calls the PC "Nana" instead of the chosen name. Also, thanks for the assist. I'd have spent hours trying random stuff before I went back there for a 3rd try.
On an semi-related note, how do you get the bad end there? I've tried entering there with a few different forms but can't figure out how to get it.
Edit: Had a feeling that was the last gold chest. I had been using the different hint chests as a sort of check list. Not opening them (cause I'm stingy) but at least having a counter for undiscovered forms.