Humanoids undergo the Trial of Grasses, to be mutated into Witchers. Once this mutation has occurred, they have access to the witcher signs, keen sight, better strength and reflexes. Taken in as children, witchers are subjected to an intense mutation. Then continue physical and magical training to make them dangerous and highly versatile against their vast array of opponents, many of which possess superhuman speed, strength and/or other deadly powers. These procedures ultimately mean that each fully-trained witcher is a mutant built specifically to hunt and kill both human and inhuman prey.

Spellcasting

During the trial of grasses, the humanoids are granted the ability to use the five witcher signs

Witcher Senses

The trial of grasses has improved your senses to help fight impending doom. One of the main mutations is the witchers eyes.

At level 3 you gain darkvision.

Ancient Signs

After undergoing the trial of grasses, the witcher is able to utilize the five signs to perform various magical abilities.

At level 3 you get the spells Axii, Aard, Igni, Quen, and Yrden.

 

Witcher School

All witchers must choose a school to finish their training. Once you choose a school, you will craft a medallion for that school and reap the benefits of that schools training.

The Bear School

Witchers who choose this school are known for their massive size, and brute strength. When you choose this school you gain +4 to STR, -4 to DEX, and +4 to AC.

The Cat School

The witchers who choose the Cat school are known to be faster than most. In choosing this school you gain +3 to STR and DEX, and your DEX modifier is added to your attack.

The Griffin School

Witchers who choose the school of the Griffin are similar to those of the wolf, they just tend to focus more on the five signs. You gain +1 to all stats and the limitation of the conjuration based signs goes from 3 per long rest, to 6.

The Viper School

Those who choose the viper school are known to be unpredictable. Those who choose this school gain +6 to dex, attack modifier is changed to dex, and poison modifier is added to attacks.

The Wolf School

The Wolf school of witchers is considered the most balanced of all the classes. By choosing this school you gain +1 to all stats, and gain +2 to your AC.

Whirl

Witchers are adept at taking down multiple enemies at once.

At level 10 grants the ability whirlwind attack: You can use your action to make a melee attack against any number of creatures within 5 feet of you, with a separate attack roll for each target.

Silver and Steel

Witchers carry two swords for their work: Silver for monsters, Steel for humans.

At level 15 you gain +2 to your hit roll when using your longsword.

Witcher of Legend

At this point you cannot go into a single tavern without someone knowing who you are. You have hunted so much, that you are a veteran of your craft.

At level 18 you gain +2 to Strength, Dexterity, and Intelligence, and you can now cast all five signs as a bonus action.