Shadow Stalker
The School of the Viper rarely will produce an exceptional individual that has great promise. They entrust them with Shadow Arts granting them supernatural powers related to stealth and assassination techniques. They are rarely mentioned and even more rarely seen. They are shadows that appear and disappear leaving only a corpse as evidence of their existence.
Subclass Features
Shadow Arts
Only Witchers of the School of the Viper are entrusted with Shadow Arts. You have the following features from these secret teachings
Shadow Teleport: You leap from shadow to shadow. You can use a bonus action and teleport to a point you can see within 60 ft of you that is in Dim Light or Darkness.
You can use this feature a number of times per long rest equal to your WIS modifier (Minimum 1).
When you attack a Surprised creature or a creature you have advantage on the attack and have not damaged the creature this combat you deal an additional 3D8 damage instead.
Hide in the Night
You know how to vanish from the field of view. You can take the Hide action as a bonus action while in Dim Light or Darkness.
You can use this feature a number of times per long rest equal to your DEX modifier (Minimum 1).
Secret Sign Umbre
Incremento is the alchemical sign for shadow. It is a specialized Witcher Sign used exclusively by the Shadow Stalkers. You can this Sign in the following ways
Create Shadow (0 Stamina): You make the Sign of Umbre as a bonus action. You create a patch of Dim Light within 60 ft of you in a 5 ft cube.
Shadow Weapon (4 Stamina): You make the Sign of Incremento as an action. You weave together threads of shadow to create a weapon of solidified gloom in your hand. This magic weapon lasts for one minute. It counts as a simple or martial melee weapon with which you are proficient. It deals 2D8 Psychic damage on a hit and has all the properties associated with the weapon. If the weapon has the ammunition property it generates its own ammunition. In addition, when you use the weapon to attack a target that is in Dim Light or Darkness, you make the attack roll with advantage.
If you drop the weapon or throw it, it dissipates at the end of the turn. Thereafter, while the Sign persists, you can use a bonus action to cause the sword to reappear in your hand.
Shadow Shield (2 Stamina): You use a reaction to make the Sign of Incremento. When an attack is made on you you can create a shadowy force that appears between the danger and you granting you a +4 bonus to AC.
Killer of Man
Unlike other Witchers you have no issue with taking out humanoid targets. In fact, it's much easier money most of the time. You know humanoid anatomy intimately granting you a 1D6 bonus to hit and damage on all humanoid targets. In addition your critical hit range on humanoid targets is increased by 1 (19-20).
Advanced Sign Umbre
You can use the full potential of the Sign of Umbre. You can use it in the following way
Create Shadow Doppelganger (10 Stamina, Inscribed): You use an action and inscribe the Sign of Umbre on a portion of Dim Light or Darkness. The shadow coalesces into an exact replica of you made of darkness. It has an AC equal to yours and has hit points equal to your Witcher level + your Proficiency Bonus and remains for 10 minutes. You can see what the doppelganger sees and you can act using your doppelganger though you use the same pool of resources such as actions, bonus action, reaction, movement, and Stamina (For instance you can make one attack with the attack action and your doppelganger can use the remaining attack available). The doppelganger must remain within 120 ft of you or 300 ft of you if the area between you and it is within Dim Light or Darkness. The doppelganger moves as if in Difficult Terrain if in Bright Light and attacks with disadvantage in Bright Light.
You can expend 1 Stamina per minute after the first 10 minutes have passed to maintain your doppelganger.