Eiro swam into the tower's top floor. Just as it was in the tower in the elemental plane of fire, it was fairly small but still larger than the demon would have expected. Though he was still far behind the fire duplicate, the only thing that really divided them was this top floor, and the book of the first incarnation of Morgan la Fey. The others were still far too tough to crack right now, so Eiro would have to increase his understanding of each of the skills used in their sealing before he could open them.
As he looked through the books on this top floor, just as he hoped, he found hints about the locations and migration patterns of the elemental plane's guardians. Eiro should be able to find them easily enough with this once he felt ready to actually venture out.