Exorcist
Undead are a constant problem but can be lucrative for Witchers that can deal with them. Exorcists use a variety of means to communicate with, banish, and destroy the Undead. They are laden with bits and bobs they use for their craft. Some unscrupulous Witchers use their knowledge to perform seances but that is viewed with anger by other Exorcists who will seek to defraud those that turn to that practice. (This is a highly specialized subclass that deals a lot with roleplay and is not suitable to every situation, discuss with your DM if this is suitable for the campaign.)
Subclass Features
Communicate with the Dead
The first step in many instances to destroy the undead is to communicate with the undead. Knowing a bit about their old life can make it much easier to know how to proceed and can uncover several mysteries. You know how to use Tarroka Decks, Spirit Boards, Mirror Gazing, Spirit Boxes, and Crystal Balls for this purpose. You have one of each and can consult with them once each per long rest. You can regain the use of one of these methods by expending 1 Stamina.
Tarroka Deck: The Tarroka Deck can be used to communicate with pieces of the Undead that are too far gone to speak much less be a threat. Usually Undead between 100-1,000+ years old that have lost their will communicate with the Tarroka Deck. You pull 4 cards in a diagonal from top, right, bottom, and left in order and set one to the side. Flip the card to the side. If it is an odd card or a face card there is a spirit willing to communicate. The top card will indicate their current mood. The right card indicates the manner of their death. The bottom card indicates their biggest regret. And the left card indicates the answer to one simple question. (For example, the Artifact on top may indicate interest in you. The Broken One on the right may indicate exhaustion or suicide. The Druid on the bottom may indicate a loss of ancestral land or crime against nature. The Illusionist on the left may indicate that the answer to your question is not what you think it is according to your current understanding.
Spirit Board: The Spirit Board has the full alphabet in Common along with a place for YES and NO and the numbers 0-9 in Common as well and a Planchette that is a clear crystal with a flat bottom. The Spirit Board is used to communicate with incorporeal spirits and follows the rules of the spell Speak with Dead. After finishing a session on the Spirit Board, make a Religion check. On a 1 you know that you were not talking with a spirit but a Fiend and there is a chance that it may have stuck around. On a 2-10 you know that the spirit was malicious and lied. On 11-20 you know the spirit was honest.
Mirror Gazing: Mirror gazing requires silence, darkness, and a special mirror inscribed with sigils and an extended period alone. It is used to communicate with spirits bound to certain locations. You can spend one hour in solitude and complete Darkness to gaze into the mirror. Make a Religion check after one hour and on a 1-4 You see a nightmarish vision and take 2D6 Psychic damage and you roll your next check to Mirror Gaze with disadvantage. On a 5-8 you see unsettling images but you know they are meaningless. On 9-12 you see frightening images that may be applicable in the next 24 hours. On 13-16 you see a comforting image that is nice but not useful. On 18-20 you see a vision that is highly applicable to your current situation.
Spirit Box: The Spirit Box is an oddity. It is a clearly manmade box with hinges on the back, perforated openings on the top of the box, a key to wind it on the side, and symbols on each side. Though it has hinges it cannot be opened by any means short of powerful magic. It only works on spirits and physical Undead such as Zombies that were killed less than 48 hours prior. You can ask one question and wind the key 1-4 times as a bonus action. The response of the spirit can be seconds multiplied by 10 equal to the amount of times the key was wound but it the response is shorter than the allotted time the Spirit Box plays horrid sounds of wailing and screaming that cause each creature within the Spirit Box to make a WIS saving throw DC 15 taking 1D10 Psychic damage for every 10 seconds longer it played than necessary or half as much on a successful save.
Crystal Ball: The Crystal Ball is a cloudy sphere of quartz on a stand made of oxidized copper that is covered in sigils. The Crystal Ball only works on spirits and physical Undead such as Zombies that have been around for less than one month. You can gaze into the Crystal Ball as an action and make a Religion check as it shows an image in the cloudy crystal as it swirls. On a 1-5 the image shown is the target’s greatest fear. On 6-10 the image shown is how the target looked like in life. On 11-15 the image shown is the target’s greatest desire. On 16-20 the image shown is one thing that the target would like you to see or indicate. You can also choose any option that is less than the result of the check. For instance, if you roll a 14 you can choose to see what the target looked like in life instead.
Destroy the Undead
You have various holy baubles, holy symbols, religious trinkets, and other paraphernalia that aid you in fighting the Undead and Evil Aligned creatures. When you make an attack if you hit an Evil Aligned creature you deal an additional 1D6 Radiant damage. If you hit an Undead you instead deal 2D6 damage. In addition, your nonmagical weapons and unarmed strikes are able to deal damage as normal on Incorporeal beings.
Sense the Unnatural
You have honed your senses and attuned them to the unnatural. You can sense beings not native to the plane of existence you are on within 120 ft of you. If they are an Undead you know what kind they are as long as their CR is less than your Witcher level (For instance, as a level 7 Witcher you could identify the presence of a CR 4 Ghost or a CR 5 Wraith).
Banish the Undead
You have developed specific rituals and prayers taken from a wide range of areas to combat the Undead. You have become a bane to the Undead. You can use an action and pray and make symbols and Signs requiring 4 Stamina. You can force an Undead within 60 ft of you to make a CHA saving throw DC equal to your Sign save DC, if the target has 50 hit points or fewer it automatically fails the save and you banish it. The creature vanishes into a harmless demiplane. While there, the target is Incapacitated. It remains there until for one minute, at which point the target reappears in the space it left or in the nearest unoccupied space if that space is occupied. On a successful save the target takes 3D8 Radiant damage.
Enemy of Undeath
Your faith, power, and knowledge has increased the potency of your Destroy the Undead, Sense the Unnatural, and Banish the Undead features. The range of your Sense the Unnatural feature is extended to 300 ft. In addition, the damage of your Destroy the Undead feature is increased to 2D6 to Evil Aligned creatures and 4D6 to Undead. Finally if an Undead succeeds the saving throw of your Banish the Undead feature it takes 5D10 damage.