Admittedly, this is a dragon -- in a fantasy universe, no doubt, but there do not seem to be flammable materials coating the walls of the corridor. I may have missed it, but our enhanced healing factor likely also leads to increased stamina (though I don't like the odds of us outrunning a dragon).
We don't know much about the dragon's physiology, but assuming it needs to breath, and that its breath attacks are actually breath attacks, then it may not have great range, as getting air to move far away is very hard to do, even with a powerful diaphragm (like a powerful air cannon, for instance).
There's also the fact that fire tends to disperse rather quickly unless you have some sort of liquid or solid fuel very close to it, assuming the dragon does, of course, spew fire.
I'm honestly just hoping that the dragon is merely mischievous or wise, and riddles are the key to the spell-book... and that the
dragon does not have the power of weather manipulation, void, and flame.
...though running may not be an option.
Hopefully it can't fit through the tunnel?
Edit: Maybe we should have headed back the way we came when deciding on an artifact. On the other hand, this temple does share several things in common with That Little Shop That Wasn't There Yesterday, and may have disappeared had we tried to return.
Magic is
so annoying to formulate plans around.
...which is another reason I'm happy it seems to be our focus.
We can
make tropes apply to us, dammit.
Bending reality in a universe with fate at the helm is immensely useful.