"Tell me about it.  I would appreciate a rundown like the one you gave me for vampirehood, but in particular: how difficult is it to learn to use, and can it affect magic from universes other than its universe of origin?"

He has given this explanation before. He can share all the details, too, since this world apparently is not going to torture or kill any people based on their hair colour with magic. He details all of it, including answers to the questions he's been asked before and clarifications on subtler points.

"To be clear, are gifts a different sort of idiosyncratic personal magic from the kind that turning sometimes gives or enhances?"

"They are. The idiosyncratic magic related to vampirehood does not typically run on a battery and tends to be personality-based or at least—influenced."

She nods.  "I think I'll want you to work with Zacharias, to find points of synergy between your magic and ours.  Zacharias is one of my best Wellspring engineers; he's in charge of several projects that could turn the tide of the war.  How familiar are you with our magic?"

"Tobin gave me a one-paragraph explanation of each aspect of it, but that's all."

"I can give you my explanation now, but as I say it's not my area of expertise, and Zacharias would have to fill in the gaps later; or you can wait until you've met him and hear it then, as you prefer."

"Waiting sounds best, then, least time wasted."

"I'll send him my notes on vampirehood and sorcery, and he can contact you when he's ready to go to work.  In the meantime, I can arrange for a room for you to stay in; based on your description of vampirehood it doesn't sound like you need very much to be comfortable, but do feel free to correct me if I'm wrong about that."

"I don't really need anything at all, not even a room. I could stay on a roof or some quiet corner.—I'd appreciate books, though, to pass the time."

"We have a library."  She gives directions, to his room and to the library and to her office and to Zacharias's lab.

"I presume Zacharias is not there?"

"He is, but he's working.  I'm going to have him look over my notes before he starts working with you, so you don't have to give the same explanations twice."

"Ah, I see."

Library-wards, then?

Librarywards indeed.  This particular library divides its books into "narrative" and "reference" rather than fiction and nonfiction, and further subdivides "narrative" into "bright" and "macabre" rather than any familiar genres.  The "reference" section contains mostly histories of Tairil, books on battle tactics geared toward small groups of powerful individuals fighting enormous monsters or armies of smaller monsters, and textbooks on magic.

Battle tactics seem most useful.

Versus big dragons: attack rapidly and frequently.  Coordinate attack patterns beforehand with your squadmates.  Unless you're facing something called an Amphithere, you're probably faster in the air than your opponent; it's often better to dodge than to block.  (All the guides seem to assume their readers can levitate and zoom around in the air pretty much however they want.)  The fact that you will reincarnate if you die does not mean death is tactically insignificant; take steps to protect your life.  Follow your squad leader's orders, because it's more important to act as as a coordinated unit than to implement every possible good idea.

Against "most varieties" of dragons, destruction of the brain "or brains" of a dragon will kill it, but they don't seem to strictly speaking need any of their other organs.  Hydras, apparently, can survive without any heads.

Dragons seem to come in varieties, which tactical manuals assume the reader is already familiar with.  He can discern a few details by implication, though.  Wyverns, the kind he fought, are most similar to folkloric dragons, with two legs instead of four.  Hydras seem to heal a lot better than other dragons, and can grow extra heads.  Amphitheres are faster, and, by implication, might not have limbs.  Salamanders' actual bodies are comparatively minuscule, and are usually surrounded by nonspecific environmental hazards, the sorts of things that Wyverns might exhale.  Wyrms are rare, enormous, and dangerous.

And all these names are translating to things he already knows so this is helpful. He memorises this to ask questions later.

After a time, a tiny, vaguely squirrel-like root creature scrambles up the bookshelves next to him and proffers a small, rolled-up piece of paper.

He accepts it with a "thank you."

The creature scurries away.

The note says:

Sadde - 

i read over Eleanora's notes.  i'm ready to talk shop whenever you are.

...with directions from the library to Zacharias's lab.  It's signed "Rias."

To the lab he goes.

The lab, as near as he can tell, is near the center of the facility.  Sadde enters onto an elevated walkway above a chamber containing an array of coconuts the size of small rooms, suspended a few feet above the ground by thick vines.  Against the opposite walls are tables strewn with piles of notes, leaves, bowls of what look like deep-fried crickets, and a few small stone birdbaths.  Someone, presumably Zacharias, is hunched over one birdbath.

He looks up when Sadde enters, and claps his hands.  "Aha!  Sadde!  You're Sadde, right?  Am I saying that right?"

"I am, and you are. It is a pleasure to meet you." He walks over to Zacharias.

"Yeah, you too.  Salted cricket?  No, you don't eat, right.  So, I hear you can do lotsa magic really fast."