Mythological creature? Wait until you see next thread...
But, sure! I definitely like that idea. In fact, if you look at the draft framework for PtH, you see the plan goes something like this:
PtH 6: My universe (alternate Earth/Magic world)
PtH 7: ?
PtH 8: Fire (Phoenix Gate)
PtH 9: Eye (of Odin)
PtH 10: Ice (Unsure)
PtH 11: Time Matrix
So, PtH 7 really needs a setting...which could be, totally or partially, Tarsis. (Or Tarsis could be a setting in a later thread, of course.) That's from a purely plot standpoint. What do you think?