Homebrewed an adventure for my main group, in which they tracked down a Lindworm for treasure. (Or the "Rotrary treasure beast" as they called it). Figured i could share it's statblock. Feel free to give feedback, or use it yourself!
Lindworm.
HP: 45
ARMOR: 3
Movement: 10
Ferocity: 2 (Or equal to the party -1, to a minimum of 1, if you wish to make it a bigger threat.)
Among scholars, the Lindworm is a beast of mystery. On one hand, it shares many noteworthy traits with Dragons, both being great reptilian beasts who covet gold and treasure, which it hoard within its lair. But on the other hand, it lacks their wings and fiery breath, and instead employs deadly venom, and the ability to bite it's tail to roll at great speeds. They make their lairs underneath old, forgotten ruins, or digging out a den underneath ancient oak trees.
Wheel Roll: Outside of combat, the Lindworm can travel at great speeds by biting the tip of its tail and roll like a wheel, doubling the distance it can cover on land akin to players on horseback.
Weakness- Severed Tail: A character can attempt to sever the Lindworm's tail with a slashing weapon, making the roll with a bane. On a hit, the Lindworm takes damage as normal, but it's tail get's damaged. On another successful hit on it's tail, the tail is severed, and the Lindworm can no longer use attack 6. If the Lindworm is stunned, you make the roll without a bane and it is severed in one hit, and if you roll a dragon regardless of it's condition, the tail is severed immediately. After a shift, the tail starts to regrow, and can be cut again, following the same rules but without a bane. After another shift, the tail has fully regrown.
1: Body Slam!
The Lindworm lunges forward, bashing its target with its body. The Character takes 2d8 bludgeoning damage and is thrown 2d4m away from the Lindworm, landing prone.
2: Venemous Bite!
The Lindworm snaps after a Character with its jaws, dealing 2d8 piercing damage. The target must then roll a CON save against Lethal Poison with a potency of 12.
3: Tail Swipe!
The Lindworm swipes around it with its tail. The targeted player character takes 1d8 bludgeoning damage and is knocked prone.
4: Foul breath.
The Lindworm huffs and hisses, letting out a foul and caustic stench. Every Player Character within 6m must make a CON roll, and become Sickly on a failed roll.
5: Threatining display!
The Lindworm locks eyes with its target, rears up, hissing loudly, and reveals its fangs. The targeted Player Character must make a WILL check against a FEAR attack.
6: Crushing Wheel!
The Lindworm bites onto the tip of its tail before rolling forward like a wheel in a straight line, the distance equal to its maximum movement. This movement can not provoke Free Attacks, can move through blocking characters, nor does it use up the Lindworm's normal movement. Every adventurer caught in its path must succeed on an Evade roll (Action), or take 3d6 bludgeoning damage and be knocked prone. If the Lindworm hits a solid surface such as a rock wall, a large, sturdy tree or a cart, the Lindworm immediately stops its movement, and becomes stunned, losing it's next turn. To use this attack, the Lindworm must position itself so it can at least move over two player characters in a straight line.