Garrthorn

Garrthorn are rare but relentless manifestations of elemental wood and subterranean rot. They arise where a strong vegetal spirit finds a deep wound in the land — a mine, quarry, or long-abandoned stronghold — and extends its influence inward. Over years the spirit feeds on the memory of the site: rats, discarded timbers, prisoners' breath, and the damp spoil of stone. As it grows, it weaves its roots through masonry and sets down anchors in the dungeon's foundations, gradually usurping rooms and corridors. Scholars at the Fieldward Archive recorded one Garrthorn that infested the old vaults under Fallowdeep. The historian Merrin Thale wrote of corridors that tipped toward sinkholes and a chapel whose altar had become a thicket supporting luminescent fungi. The Cult of the Hollow Sheaf, who venerated controlled growth and the reclamation of manmade waste, have been known to coax fledgling Garrthorn with rituals of compost and root-binding; such cultists seek Garrthorn deliberately, believing the spirits can be guided to reclaim blighted towns. Parties who encounter a Garrthorn are often surprised to find it selective: it protects certain chambers like a steward while hollowing others for nursery chambers of seedlings and fungal beds.

Garrthorn stands roughly the size of a medium cart when rooted, its main trunk-like torso rising four to six feet with a weave of knotted vines and exposed heartwood. Bark plates form overlapping armor that is furrowed with old lichen and mineral streaks from the dungeon's stone. A crown of thin, whip-like roots and small leafy shoots lashes from its shoulders and back; some roots are pale and fleshy where they probe mortar, others are blackened with sap and fungus. Its face is a suggestion — a flattened knot of wood with two slow-glowing amber knots like eyes and a mouth that opens only to reveal rows of serrated inner bark. Limbs end in heavy, clubbed root-hands or flat, shovel-like palmate fingers used to lever stones. Sections of masonry and clay are integrated into its form — a slab of flagstone for a shoulder, a shard of column for a kneecap — making it look like a living graft of dungeon and forest.