Zygom

A zygom looks like one or two dozen small mushrooms, each a thin stalk with an egg-shaped cap. A shared root network links them into a single communal organism.

The zygom never truly attacks. A creature that roughly disturbs a colony has a 1 in 6 chance of breaking a cap and being smeared with pale blue sap. This 'milk' bonds whatever it touches for 1d4+1 days before drying to powder, so blades stick to targets and creatures to one another. Sap on bare flesh carries spores, and by the time the glue crumbles the fungus has rooted in the victim and begun steering it.

Its thinking is so alien that mind-affecting magic, including charm, hold, hypnotism, beguiling and domination, has no effect on it.

Zygoms grow only in a remote mountain range, for reasons unknown. Sages think they came from another world. A deliberate invasion seems unlikely, since a real one would use many landing sites rather than risk lava, ocean or ice, so most believe they arrived by accident. Whether that is good news is still argued.

Soil will sustain a zygom, but it prefers feeding on a living host's blood and tissue. Favored hosts include giant ants and rats, big badgers, bear cubs and occasionally small humanoids such as dwarves, gnomes and halflings. A man-sized or larger host is possible but would likely require someone to lie down right on a patch.

The growth spreads over the head, neck and spine, linking into brain and nerves, and the zygoms then dictate how the host moves, fights and defends itself. Death comes in 1d8 weeks depending on size and constitution: a tiny worker ant might survive only a week or two, a sturdy halfling six or seven, perhaps long enough to find help if the fungus allows. The colony stays on the corpse until all of it is consumed. Apart from rare magic such as wish or alter reality, only cure disease removes it.