The Basics

Tomemancy is split into 8 elements or categories of magic. These are Pyromancy, Hydromancy, Ecomancy, Atmomancy, Fulmamancy, Necromancy Mystomancy and Lumomancy. Each have Tomes specific to them. On spawning into the world, the player receives a random Page that grants them one of these elements.

Tomemancy is even further broken down with Tiers. These tiers are very important as the caster has to be the same Tier as the Tome to cast it. They are Basic, Apprentice, Acolyte and Advanced. For more information, check the in-game guidebook, "Tomemancy 101".

There is a special Tome that holds no Element. To acquire this Tome, interact with a wizard of any kind while holding a book.

Some Basic Tomes: 

Pages

Pages are just what their name says they are. However, these pages are very important. Pages hold esoteric and obscure knowledge about the elements of Tomes. It is required to read a Page of an element before you can cast any Tome of that element. For example: You are required to use the Page of the Seas if you wish to use any Hydromancy Tome. As a reward though, using a Page grants a Basic Tome of the element that Page unlocks. The Pages are:

The Page of the Seas: Unlocks Hydromancy Tomes
The Page of the Nether: Unlocks Pyromancy Tomes
The Page of Nature: Unlocks Ecomancy Tomes
The Page of the Storms: Unlocks Atmomancy Tomes
The Page of Curse: Unlocks Fulmamancy Tomes
The Page of the Mystic: Unlocks Mystomancy Tomes
The Page of Light: Unlocks Lumomancy Tomes
The Page of the Undead: Unlocks Necromancy Tomes
The Page of Unbridled Magic: Unlocks all Tomes (this Page grants no Tome on use)

Wizards

These are the beings that created these Tomes. More information on this subject can be found in the in-game guidebook "Tomenomica Historia".

Wizards are neutral mobs, though they tend to be vicious to Illagers for reasons set down in history, but that is not as important as their main purpose.

 
Players can trade with the Wizards for most Tomes. And warning: Never hit Wizards unless you want a face full of spells.

Wizards come in four variants, each with a different type of trade. Green Robed Wizard trade Basic Tomes, Blue Robed ones trade Apprentice Tomes, Purple, Acolyte Tomes and Red Robed Wizards trade Advanced Tomes. They also trade Grimoires or "Tomepedias" for their respective Tiers.

Level Importance

You may also want to save your levels because in order to cast Tomes you are required to match the Tome's XP requirement. In fact, it is your level that determines the Tier that you are at. Lvl 0-15 means you are at the Basic Tier, Lvl 16-30 is the Apprentice Tier, Lvl 31-45 is the Acolyte Tier and Lvl 46 and above means you are within the Advanced threshold. This specific rule prevents Mages from going from Tomes like Douse to Tomes like Lightning Storm in a short period of time.

And Warning: You may not want to die, if you are of a very high level. You do not lose your Magical Knowledge but you will be reset back to the Basic Tier if this happens. You have been warned.

Tomecrafting Table

The Tomecrafting Table can be used to craft Basic Tomes. For more information, see the "Tomenomica Historia", Page 21. It is crafted with 3 stripped spruce logs, 1 gold ingot and 3 emeralds.

Hematurgy

Hematurgy or "Blood Magic" is another feature of Tomemancy. While this area of magic does not use Tomes(in the way you think), levels or Pages, it still requires a Wizard. Wizards and Players created Hematurgy together as documented in the grimoire, "A Hematurgist's Guide". Players may try to trade with a Wizard for this grimoire, but it can also be crafted with a book and an Iron Dagger.

Top Image: A Hematurgist's Guide, Bottom Image: Iron Dagger

By taking an Iron Dagger, you can interact with a Wizard of any Robe color and they will enchant it for you, turning it into an Enchanted Dagger. With this Enchanted Dagger, you can lay Blood Sigils.

By looking directly down and long pressing with the Enchanted Dagger, you will damage yourself and form a Base Blood Sigil at your feet. You can interact with this Sigil while holding different items to change the Sigil into other kinds of Sigils.

Hematurgists (persons who practise this art) have left a myriad of grimoires around the world in different structures, detailing different types of Sigils and how to create them.

Example Image

Blood Sigils can also be concealed, making them deadly traps. By using an Ink Sac, you can make any Sigil(except for the Base Blood Sigil) completely invisible. This tactic is especially effective, however do not step on the sigil if you are not sure of its sigil because it will activate. If you wish to dispel this invisibility, use the glowing variant of the Ink Sac.
If you want to see them somewhat through their invisibility, using a map can prove to be helpful. They are highlighted as red dots.

That's it for the basic explanation of the add-on. Any additional information can be found in the "Tomenomica Historia", "Tomemancy 101" or the "A Hematurgist's Guide". All information on Tomes and their usage can found in one of the 4 Tomepedias.

Scrolls and Staves Update (What's New?)

This update adds Scrolls, a new way of casting magic even though it has it's limits, and Staffs, new weapons that do 5 dmg on hit as well as being able to cast specific spells (they are also enchantable. Do with that what you will).

Scrolls can only be found and are essential for crafting Tomes and Staves.

Crafting staves requires an Orb and a Staff Base.

The Staff Base Recipe

There are 5 Orbs.

Emerald

Scroll: Scroll of Druidic Missile

Diamond

Scroll: Scroll of Resistance

Amethyst

Scroll: Scroll of Druidic Missile

Quartz

Scroll: Scroll of Firebolt

Copper

Scroll: Scroll of Lightning Bolt

After you craft an Orb, you then combine it with a Staff Base to get the finished product!

The Tome Table has also changed its look and has gotten a new crafting recipe.

Thanks for playing my add-on😊

Credit where it's due:

@TheGibberishOne for the amazing wizard model, textures and the cover image

@Fireblast for the Scroll textures

@KekeCreations for help with NBT editing

@Grimm for helping me figure out how to name the Wizards on spawn

@howlKM for creating the Tomemancy Discord Server

And everyone who suggested ideas that got added this update (even if it didn't get added now, I still appreciate them :])

If you plan to review or showcase my add-on, be sure to credit me and use the original link. I spent a good deal of my free time on this add-on, so let's not disregard that.

And please refrain from providing any download link I did not create.

Also, look out for another project I've been working on that's coming soon!😉