You also have the Travelling Shop and the Domination Medal Exchange Shop as options, which both sell Magic Tomes for Magic Pages or Domination Medals.
Where To Get Magic Tomes
Here are more details on all of the sources of Magic Tomes in the game.
Source #1: Chaos Fields (Best Source)
The Chaos Fields will always be the #1 source of getting Magic Tomes and Magic Tome Pages in the game. For that reason, and also since you can farm a ton of other useful items here, I advise AFK farming the Chaos Fields often. Do it daily if you can spare either your AI Mode time or your IRL time by leaving the game open and just letting the Auto-attack system do its work while you do other things.
Source #2: Travelling Shop
The Travelling Shop sells several account growth items like Specialties, Soulstones, Puzzle Packs, and Ingredients. You can also exchange your Magic Tome Pages for Magic Tomes here. They spawn at random locations all over the World Map, and each shop only stays at a specific location for over 30 minutes. You can keep track of Travelling Shops by checking the in-game announcements or by simply going to the World Map and checking which zone they’re currently in.
Source #3: Domination Medal Exchange Shop
The Domination Medal Exchange Shop is another excellent source of Magic Tomes, where you only need Domination Medals to be able to buy them. You’d always want to keep an eye out for this shop, as the Magic Tomes sold here are very useful if you want to focus on a specific class or playstyle. Passive-type Magic Tomes that boost your CP are also available here, which is why I recommend you farm Domination Medals regularly and pick up as many as you can from this shop every week.
Source #4: Dimensional Border Bosses
Dimensional Border bosses drop unique, Active-type Magic Tomes that can be very helpful for most PVP and PVE content. The drop rates for all Dimensional Border-exclusive Magic Tomes are pretty low, but if you hunt the bosses consistently, any of these skills can eventually be upgraded to high levels. I recommend that you focus on farming one Dimensional Border boss at a time, especially since each of them also drops different Dimensional Border-exclusive accessories.
What Are Magic Tomes Used For?
Magic Tomes are used for both learning new Skills and upgrading existing ones. There are three kinds of Magic Tomes in NNK:CW: Your choice of which Magic Tomes to invest in is crucial, as your playstyle is highly influenced by the Special Skills that are available to your character. This is exactly why I recommend that you focus only on buying or grinding for a few Magic Tomes, just so you don’t spread your resources way too thin.