Wood woad

Wood woads were powerful humanoid-shaped guardian plants. Each wood woad contained the soul of a creature that (willingly or otherwise) gave up its life in order to eternally perform a given duty.

Description
The ritual that created a wood woad consisted of removing the heart of a living person, planting a seed into it and placing it inside a cavity in a tree. The sacrificed creature's body was buried in the vicinity, and the tree was then bathed with the sacrifice's blood. After three days, a wood woad would sprout from the ground nearby, ready to receive its orders, which it would then follow forever or until otherwise relieved.

Wood woads that were freed from their duties sought others to serve and protect, and would commonly ally themselves with druids and treants.