Hit Points: 1d4
Wizards study the fundamental powers of reality. Which their minds reduce down to words of power. Each word a wizard knows is a core concept that shapes reality. They can be mystical like the word 'Light', or as mundane as 'Door'
Can learn magic words (and starts with 1d4+1 spells worth of magic words at 1st level).
Magic words can be used to perform cantrips, as well as draw on the knowledge/perception of the world around the wizard as focused through the word’s domain.
The wizard creates spells using two or more magic words. At end of the session (assuming the Wizard has time and peace to study. Even just a night at camp is enough) the player presents name, words used, and concept. DM creates spell and gives it to player next session. Spells don't have levels. Most variables in a spell will be based on Wizard's class level.
A wizard may know as many spells as they want. Each wizard has a spellbook (or several) that records all of the spells they know, both the spells themselves and every detail (related or not) of the creation of each spell. A wizard may only prepare a number of spells equal to their Intelligence modifier plus their level.
A wizard needs to be able to speak (at least a whisper) and be able to gesture with both hands to cast spells.
Casting spells is a magic skill check. 1d8. If result is lower than wizard’s number of mystic mutations the spell is cast normally. If result is higher than number of mutations, spell is cast normally and wizard gains a new mystic mutation. If result is 8 or higher, the spell goes off, magic surge happens, they gain a mutation, and the spell is lost from the wizard's mind until it gets prepared again. Mutations are both good and bad. If a wizard ever gets 9 mutations, they are completely overwhelmed by the magical corruption and become NPCs unconcerned with anything they might have cared about before. On the other hand, a Wizard can multiply any spell effects by the number of mutations they have. So a wizard with 2 mutations casting a 3d6 damage fireball spell can make it a 6d6 damage fireball.
Magic surge is another 1d8 roll. Odd numbers are magic surge of the spell and the results 1, 3, 5, and 7 are in each individual spell. The even results (2, 4, 6, 8) are environmental effects and are listed in each terrain/environment the PCs are in. In general, 1-8 is ascending level of power/seriousness. Wizards can figure out the spell surge effects if they make an effort, but location/environment surge effects can only be discovered when they happen.
Some spells have no listed duration. This means that a wizard can maintain them for as long as they wish. A wizard may maintain as many spells as they wish, but every ongoing spell adds a +1 modifier to further spellcasting magic rolls.
Wizards can build/maintain a laboratory.
Spells can be cast as rituals without the risk of mutation. Still risks a magic surge, but only location results count on the second surge roll. Casting a spell as ritual requires a lot and the level of the lab is used for caster level. Material components are used for risk free casting while away from laboratory.
Spellbooks as treasure will created and/or otherwise placed as normal. Only the magic words of the spells can be learned. Though the basic nature of the spells can be deciphered with study. Spell concepts make creating similar spells easier.
A scroll can be used to cast the spell on it, using it up. Or it can be studied and one word of the spell can be learned. Which uses up the scroll just like casting the spell from it does.