"If they exist where I'm from, they keep themselves hidden so well that even the gods do not know about them." Which isn't totally impossible, the Greek gods are not omnipotent, but Prometheus can't help but feel like he'd know about their existence. He's been around long enough.

A blowtorch isn't going to work, either, but Prometheus doesn't have the heart to continuously crush Peter's hopes. The poor goblin is obviously freezing. "Would you like to go back inside? Your portal hasn't disappeared, at least. When winter ends, you should be able to return home."