This was a one shot I run in 2012 at the beginning of a Savage Warhammer campaign that never made it to session three. Basically it is more a less a generic fantasy adventure, even though it is a little bit on the darker side.
The adventure starts with the player characters taking a coach to any destination. The street leads through dense forest. At dusk, 150 metres before a sharp turn of the street, the coachman (named Falk?) stops and gets to the front to check on the two horses. Without a word he releases them and makes them run off along the street, mounting one . [I don't remember the actual way the coachman disappeared. So I just make the running to the forest part up now, as it is hard to figure out why the players would not focus on the coachman. Maybe it is Sybille (see below) shouting for help? Another creepy option would be the coachman committing suicide on the spot.]
If the player characters follow, they arrive after around 50 metres, at a clearing. There is one huge oak tree standing there. Five people are hung there - gallowsstyle. One woman is lying seemingly unconscious or sleeping at the beneath the tree.
Actually this is a set up: the women whose name is Sybille is pretending to be unconscious to trick the player group to come near the tree. The people are not hanging from ropes, but from vines. These are some of the "arms" of a dangerous plant creature that is lurking in the tree. It is similar to a giant octopus, except that it is a moving bundle of vines. Just use the game stats of a giant octopus for it! It has eight "arms" and while four are currently holding former victims by their necks, the other four will grab whoever comes near the tree. The vine octopus is patient enough to wait for more than one person to move into his range (2" or 4 metres around the tree). But latest, when it seems that someone moves out of its range, it will attack.
To attack group members that did not move towards the tree, the vine monster throws the corpses it is currently holding. Only if everyone moves away from the tree, the vine octopus leaves the oak and follows. Until this moment it seems that vines have overgrown the tree. The vine monster actually is just tool for the real enemy: the "Heart of the Forest", a glowing crystal that contains the actual consciousness of the creature.
It tries to cover it up as good as possible, but when attacking multiple targets in different directions at once, it will expose it. The crystal is very hard to damage [Toughness 10, damage dice don't explode], but when damaged will detach from the vine body and just fall to the ground. The vines stop moving.
The Heart is stored in a cabin nearby, but controls the vine octopus from the distance.
The woman, Sybille, will never be attacked by the Heart of the Forest. She started serving the "heart of the forest" after a religious hermit named Vater Ewald showed up and told her that her two children that disappeared many years ago (being abducted by beastman) could return, if she started to join his dubious religious rituals. Vater Ewald is seen by the locals as pious man, but something out there in the forest - the Heart of the Forest to be more specific - turned him into a disciple of sinister forces.
Sybille who is the wife of the farmer of one the bigger farms nearby felt obligated to do so. While she rarely sees Vater Ewald who lives in a cave deeper into the woods and secretly associates with beastmen, he handed the Heart of the Forest over to her and she stored it in a cabin not far from the clearing.
The Heart started to telepathically speak to Sybille and persuaded her to bring her victims. Hoping to get he kids back, she agreed and lured known highwaymen to the oak where the Heart of the Forest had created it's vine octopus body. After doing that she realised that having more people disappear would not work well. But the Heart wanted more victims. Sybille came up with the plan to seduce a coachman travelling through every few days. All she wanted from him was to halt at a specific spot in the forest, release his horses and ride away. This way she should be able to provide enough victims until she was reunited with her kids.
(The kids are actually long dead or at least neither Vater Ewald nor the Heart of the Forest ever knew anything about their fate. He just used them to trick Sybille in collaboration.)
In a way Sybille hopes that the Heart of the Forest's creature will be slain. It's not really a good feeling running around at night luring people stronger than yourself into ambushes and see them killed - even if you rationalize that you do all of this to save your kids. She will admit the truth and tells her whole story after the vine monster is destroyed. She will lead all the survivors to the cabin nearby, where the Heart is stored.
After entering the cabin and telling about the location of it - it is hidden beneath the wooden floor -, she collapses. The Heart decides to safe itself by taking mental control of the person present with the lowest willpower (Spirit) and attacking everyone else. It can only control one person at a time, but is able to shift every round - in case a victim is restrained or incapacitated. To stop the mind control the Heart of the Forest in it's crystal form needs to be smashed. It has Toughness 12. As with any structural damage, damage dice against it don't explode. [I actually don't remember how the Heart defended back, when we played the adventure.]
After the destruction of the Heart, Sybille can be woken up again. She is in tears as she is scared of her fate and begs the player characters not to tell anyone what she did. If they agree she asks them, if they want to take her back to her home - the big farm.
(I also created this
relationship map, but don't remember what it really means. I used the names on it for the three NPCs. I probably would have forgotten about Father Ewald's role otherwise.)
Follow up adventure: the farmer hired a team of mercenaries to find his disappeared wife Sybille. When the player characters bring her back, they feel cheated about their reward and start getting more and more brutal. One of the farmhands actually is also conspiring with Father Ewald and kills Sybille before the truth can come out. If the player characters kept Sybille's dark secret, it is hard to figure out who did it and why. The mercenaries as well as the player characters are suspicious.
If the player characters tell on Sybille, she will have a witch trial with an inquisitor showing up surprisingly and suspiciously fast.
The showdown is supposed to take place in the cave of Father Ewald, who is a quite powerful wizard. On the way there the player characters are ambushed by beastmen.