Tintamancy

While all wizards are studied individuals, they are not all bookish types necessarily. Some find no solace in the pages of books as many do, and instead find their peace in surrounding themselves with arcane runes, emblazoning those symbols directly onto their body.

Living Spellbook

When you choose this school at level 2, your spellbook has been rendered mostly useless to you. You keep it yet for experimentation and research notes, but your arcane power comes from the runes on your skin itself. As you prepare new spells, the old ones fade to grey, still there and a part of your repertoire but inactive, and the new grow bold and brilliant. When you learn new spells and add them to your living spellbook, your existing spells shift around your body to make room for the new ones. Scarring does not affect the runes, but acts specifically intended to remove the skin will damage them.

When you choose this school at 2nd level, you can make a Constitution Saving Throw whenever you copy a new spell onto your living spellbook. The DC for this check is 10+the spell’s level. On a success, the time and gold needed to copy the spell is halved.

Callused

When you reach 6th level in this class, you gain proficiency in Constitution saving throws. Additionally, if you are not wearing armor or wielding a shield, you can use your Constitution modifier in place of your Dexterity modifier when determining your unarmored AC.

Skin Deep

The runes on your skin have connected themselves to your essence and can shield you from things as paltry as weapons. Starting at 10th level, when you take damage from a physical attack, you can use your reaction to gain resistance to the damage from the attack and give yourself temporary hit points equal to your wizard level after the triggering attack's damage has been applied.

You can use this feature a number of times equal to your Constitution modifier per long rest.

Inkmaster

When you reach 14th level in this class, your Living Spellbook has become even more robust, being able to hold active arcane energy as well as the runes that produce it. When you cast a Wizard spell, instead of releasing the spell, you can choose to store its energy in your skin, still expending the spell slot, time, and material components as normal.

You can use an action to release the magic. If the original casting time is longer than 1 action, it becomes 1 action for the purposes of activating this feature. A spell stored this way fizzles after 24 hours if it is not released. You can only store a spell up to 7th level using this feature and can only have 1 spell stored at a time.