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.
Beside that, though, the next thing of importance that he found was some information on the naiad king and queen. Records of the specific powers and abilities of the past and current monarchs, as well as certain weaknesses. These might not be 100% accurate, though; the books here weren't necessarily all factual. Particularly up here, as explained by the overseer, if the information couldn't be otherwise verified, it was generally treated as true. After all, false information can be just as powerful as true information, if not more so.
But even so, from what Eiro could tell, it seemed pretty reasonable. It all seemed to overlap with what he sensed from the monarchs as well, plus, Nelly was able to verify a lot of this information as well. Not all of it seemed to be perfectly true, but that was fine. It was enough.
The rest of the books were useful, certainly, but not amazingly so. Powerful spells and methods of casting magic, state secrets, massive conspiracies; the sort of thing that you would expect to see here. Just like with the ones Eiro found in the elemental plane of fire's tower, Eiro recorded the spells into his grimoire. They showed a unique perspective, but they weren't necessarily super useful for Eiro. Rather, they were just a little bit outdated, especially compared to what he was able to develop on his own.
Once he had finished reading all the books in the top floor, Eiro moved on to the secret room left behind by Morgan la Fey, where the true value of this tower laid. Of course, Eiro was able to already develop his magic by leaps and bounds by reading the books in here, and he learned numerous clues and interesting tidbids and information on useful materials, but what he could learn merely through the process of trying to unlock Morgan la Fey's books was incomparable to all the rest.
Just with a cursory glance through the room, Eiro could tell that there weren't all the same books in this space. There were some that weren't in the tower in the other realm, and some that were missing from here that were over there. Since these books were transcriptions of each incarnation's experiences in that respective realm, Eiro figured that not every single incarnation made it to every single realm. Maybe there was simply no reason for some of them to come here. Or whatever they did here wasn't worthy of being written down. Or the respective incarnations simply didn't feel like writing everything down.
Carefully, he pressed his wooden palm onto an apple; for now, the support he got from his wooden hand for casting magic should make this a bit easier. Slowly muttering the supportive chant that he developed while building the complex multi-layered arcane magic circle around the apple, Eiro cast the spell.
It cost him a lot of arcane magic, but a moment later, that arcane magic pulled apart the apple and moved it from Eiro's desk over to the coffee table a few steps away. Seeing the success, Eiro jumped up in excitement.
"Finally!" he exclaimed, grinning from ear to ear. Since this was successful, Eiro just had to iterate on this spell. Some of his mental duplicates worked on compressing the chant into a single word, while others worked on simplifying the magic circle to the point where it could be placed inside of Eiro's body by manipulating his magic circuits.
In just an hour, the simple test run had turned into a proper, decent spell, since almost all mental duplicates were working on this one particular task. This was a breakthrough that would make things so, so much better for Eiro. Not only would this catapult his battle capabilities up far, far higher than they could reach before, but his movement speed would go up.
Since the 'Ultimate Agility' card affected the scale of speed of every part of Eiro's body, that included his magic as well. With that card's effect fully unsealed inside of this duplicate's body, Eiro's magic would be able to travel from spot to spot almost instantaneously. His body could start rebuilding itself in one spot before it was even fully broken apart in another.
And luckily, this Eiro was a duplicate. He could test this spell out without needing to fear that he was going to accidentally kill himself; he could figure out what this would do to his consciousness before and after the mock short-range teleport.
Eiro stood up, and let the magic flow through him, creating the magic circle around himself, activating the newly developed 'Blink' spell on himself for the first time.