Several. [ Sometimes he's frustrated enough to try, try again, too, but that isn't a fact anyone needs to know of. ] Claws and fire do nothing against it.

[ Then he smirks. Another wishing to try his real name, is it? ]

Very sure, but if you wish to try, I'll certainly give you a chance. My true name happens to be [ Something very complicated involving rather inhuman dragon sounds (not written here, as the writers never bothered to actually reveal it; writers, honestly!) ].