|The title of this article is conjectural.|
The Breathing Spell was a spell that allowed one to breathe clean air even in those areas where it would not normally be possible.
When Eragon, Saphira and the Eldunarí of Glaedr traveled through a fierce storm on their way to Vroengard Island, Glaedr recommended this spell as a way to allow them to fly much higher than would normally be possible, so they could escape the fierce effects of the storm.
The spell both gathered clean air around them and allowed for the escaping of air that they had already breathed, so that it would not grow stale. The enchantment was immensely complex, so Glaedr had Eragon repeat the spell until he was sure that the wording was correct, and then Eragon cast it.
The spell required a massive amount of energy that was said to multiply out of all proportion in comparison to a spell that Eragon was using to warm himself and the others, leading Glaedr to provide energy to support him.