Anyways, I was thinking maybe have a certain potion or something (Say its called a transmogrifier tonic? *Snicker*) that you can quaff and the next monster you kill you would turn into.
Now, of course, there's a whole lot of problems that would arise, e.g. speed bopdy size etc I'm mainly just throwing the idea out. Pretty much all these problems can be solved by having it only show your monster identity in town e.g. you can move through people in town so having a glint block the gate wouldn't be a problem. Or you could only transform into certain predtermined monsters like tengu, blood wallows that HENCHMEN ALREADY HAVE!

Edit:Town would also look very very cool and more fantasy typed.