That's silly, fire don't even work on someone who knows magic.

[He's heard of it, but he never really thought it was true. Witches and wizards in his world can control their own body temperature to prevent overheating, so it's not much to expand that spell a little to prevent burns.]

But humans in my world at least found out about how promises work, and they try to use it to their favor. Buncha assholes, all of 'em.