Medium monstrosity (shapechanger), chaotic evil
Armor Class 16 (natural armor)
Hit Points 52 (8d8 + 32)
Speed 40 ft.
Skills Deception +6, Insight +3, Stealth +6, Perception +5
Damage Immunities bludgeoning, piercing, and slashing from nonmagical attacks that aren't silvered
Senses darkvision 60 ft., passive Perception 15
Languages Common (can't speak in beast forms)
Challenge 8 (3,900 XP)
Shapechanger. The Skinwalker can use its bonus action to polymorph into a Small or Medium humanoid it has seen, into a beast of its choice, or back into its true form. Its statistics, other than its size, Strength, Dexterity, and Constitution scores and actions, are the same within each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies. While not in its true form, the Skinwalker takes half damage.
Aggressive. As a bonus action, the Skinwalker can move up to its speed toward a hostile creature that it can see.
Ambusher. The Skinwalker has advantage on attack rolls against any creature it has surprised.
Keen Senses. The Skinwalker has advantage on Wisdom (Perception) checks that rely on hearing, sight, or smell.
Mimicry. The Skinwalker can mimic any sounds it has heard, including voices. A creature that hears the sounds can tell they are imitations with a successful DC 14 Wisdom (Insight) check.
Natural Mask. While not in its true form, the Skinwalker has advantage on Charisma (Deception) checks to hide its true identity.
Nimble Escape. The Skinwalker can take the Disengage or Hide action as a bonus action on each of its turns.
Pounce. If the Skinwalker moves at least 20 feet straight toward a creature and then hits it with a bite or claw attack on the same turn, that target must succeed on a DC 15 Strength saving throw or be knocked prone. If the target is prone, the Skinwalker can make one bite attack against it as a bonus action.
Standing Leap. The Skinwalker's long jump is up to 20 feet and its high jump is up to 10 feet, with or without a running start.
Surprise Attack. If the Skinwalker surprises a creature and hits it with an attack during the first round of combat, the target takes an extra 10 (3d6) damage from the attack.
Multiattack. The Skinwalker makes three melee attacks. In its true form, it makes one with its bite and two with its claws.
Bite (True Form Only). Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 8 (1d8 + 4) piercing damage.
Claw (True Form Only). Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage.
Shapeshifting is a frightening ability. The power to become something you're not at will is rightfully unsettling, as most creatures who wield this power are not the kindest beings. Many are cruel and brutal, and this one has a name befitting its ability. Most when they hear it rightfully feel their skin crawl.
He Who Walks on All Fours. A Skinwalker is a monstrous perversion of nature spawned by an act of defying it. The ritual to become a Skinwalker is only possible through witchcraft, so witches can become Skinwalkers. In addition, the transformation is only possible for those who have committed the most horrid of cultural taboos; murder of a close blood relative, incest, necrophilia, etc. Only committing acts that destroy one's humanity can qualify one for the dance of the Skinwalker.
Once the dance is done, the witch begins to transform. Their body begins to contort, their ribs push out of their chest, and they peel the skin off their face to reveal the bare skull of a truly unnatural creature. The skull is unique to every Skinwalker and can have a mixture of traits from any number of animals. Once the transformation is complete, there is no going back. They are no longer human, dwarf, elf, or whatever else they may have been; they are the one who walks on all fours. The Skinwalker.
The greatest ability of the Skinwalker is that to transform into any animal it pleases. A whale, a mammoth, a shrew, all are the same to it, though most Skinwalkers do favor the form of a coyote or wolf. This ability makes it meat impossible to find when they've killed, as they will usually escape in the form of a bird, a rodent, or even an insect leaving only the barest trace. A Skinwalker can also transform into individual humanoids, usually luring them out into the wild and killing them and taking their place to get to their target. However, Skinwalkers are easy to find if one knows what to look for. The oblivious clue is what the Skinwalker leaves behind after it transforms; a pile of integument and skin.
Variants: Skinwalker spellcasters and items
Some Skinwalkers maintain their magic through the transformation. A Skinwalker spellcaster ha a challenge rating of 10 (5,900 XP) and the following trait:
Spellcasting. The Skinwalker is a 9th-level spellcaster. It's spellcasting ability is Charisma (spell save DC 16, +8 to hit with spell attacks). The Skinwalker can cast detect thoughts at will and has the following warlock spells prepared:
Cantrips (at will): poison spray, minor illusion, chill touch
1st level (4 slots): hex, witch bolt, expeditious retreat
2nd level (3 slots): enthrall, suggestion, mirror image
3rd level (3 slots): vampiric touch, major image, fear
4th level (3 slots): blight, hallucinatory terrain
5th level (1 slot): scrying
Some Skinwalkers carry a blowgun made of bone and corpse dust. Such a Skinwalker gains the following actions:
Blowgun. Ranged Weapon Attack: +7 to hit, range 25/100 ft., one creature. Hit: 1 piercing damage and the target must succeed a DC 18 Constitution saving throw or take 3d8 poison damage on a failed save, or half as much damage on a successful one. If the poison damage reduces the target to 0 hit points, the target is stable but poisoned for 1 hour, even after regaining hit points.
Corpse Dust. Corpse dust is a powder made from grinding the bones of twin infants. The Skinwalker throws this dust in a 10-foot cone. Each creature in the area must make a DC 24 Constitution saving throw, taking 8d8 poison damage on a failed save and is poisoned for 1 hour, or half as much damage on a success and is not poisoned. While poisoned, the target takes 4d8 poison damage at the start of each of the Skinwalkers turns, and dies if the poison damage reduces the target to 0 hit points.