"It wasn't so bad after we escaped the giant seal..." Kentucky said, having experienced the last twelve days inside the Corridor. And he was right. It wasn't so bad since both he and Roan could enter the Dimensional Realm to recover. It's just that they spent a lot of Divine Stones and even Starlight Energy.
Since the start, only Sky Energy was truly capable of keeping them protected from the freezing energy in the Corridor during the Glacial Overflow Critical Point. Roan and Kentucky tried to save as much as possible by using only Divine Energy on everything else, but it still wasn't easy to see the amount used.