Lesovik
“The Leshy” © Toly Kivshar, accessed at his ArtStation page here
[I quite like the leshys in Pathfinder; little humanoid plant spirits are a good way to add some whimsy and wonder to low level games. But they’re a terrible representation of the actual folkloric leshy. Even the Witcher games have a more accurate leshy, and that’s something I can basically never say about the Witcher franchise. Fortunately, since the leshy is found under many different names in different Slavic cultures, I could find an alternate name easily.]
Lesovik
CR 16 CN Fey
This creature is humanoid, but made as much from wood and fungus as it is flesh and blood. Its skin is like bark, and hair, moss and lichen all grow from it, granting it a shaggy pelage and facial hair. They have antlers made of forking branches, hooves for feet, and clawed hands.
A lesovik is a fey creature that considers itself the lord of the forest in which it dwells. They watch over the animals and plants in their domain, and may be helpful or harmful to humanoids, as the whim suits them. Lesoviks are skilled shapechangers, and often take humanoid form to interact with travelers and ferret out their intentions. Those who are polite and respectful of the forest may receive aid in the form of pointing out game trails or helpful advice, but those who are rude or destructive will be led on a wild goose chase and lost in the woods, sometimes to fatal effect.
A lesovik can change its size, so it can become as tall as a tree or small enough to hide behind a blade of grass. If challenged to combat, they usually take their largest form. Any branch or stick held by a lesovik becomes a magical club, which they supplement with their natural attacks. All lesoviks are powerful spellcasters, capable of drawing from druid spells—no two lesoviks are likely to have the exact same tactics.
Lesoviks get along with other fey creatures in their forests, as long as they show proper respect. They consider treants too deliberate and stodgy, but do not try to drive them out. Most lesoviks love gambling, and when the lesoviks from multiple forests come together peacefully, it is usually to gossip and play cards. They may wager the plants and animals in their domains in these games; rapid shifts in animal distributions may be due to a lesovik paying off a debt. Not all interactions between lesoviks are peaceful, and unseasonable storms, spontaneous forest fires and outbreaks of plant diseases may be signs of a battle between lesoviks.
Lesoviks do not grant boons and banes the way some other fey creatures do; they instead use druidic magic to benefit or harm mortals respectively. Some druids were taught by the lesoviks; they tend to have the Plant or Weather domain rather than an animal companion. Lesoviks treat leshys with grandfatherly affection.