Its dependancy on a box of soil may have more to do with nesting conditions and soil fungi - tying it to the concept of the Faerie mushroom Ring.
Its top speed caused it to be visible on a single camera image frame in a distance of fifty feet so its incredibly fast. It can also lift a ton without effort and the only reason it was caught on camera was because the ton it lifted slowed it down.
A protagonist in the episode is collecting Silver so it may be vulnerable to Silver weapons.
HD: 8* (L)
MV: 12,000' (4,000')
AT: 2 Claws, Feeding Probiscus, Aura
DA: Restrain Victim / 8d8 per round/ special
NA: 1(Unique) + wight-worms
SA: Elf (L8)
ML: 12 (predicting: 6 if injured with silver, 2 when exposed to sunlight)
Description: eight feet tall 'cloak' that conceals a mother-parasite. It will be tied to its soil nesting site though it has intelligence enough to carry the soil in a coffin or other large container and has incredible physical strength (lift up to a ton). It's presence whispers in the mind of prey requiring a charisma check to resist being lured away to it's chosen feeding site. Vulnerable to silver weapons only. Ancestor to Sidhe and Banshee. Must feed on blood to survive.
Wight-worms (HD 1 1hp, AC3, MV 3'(1'), AT Burrow/infest, DA special, NA 1d10, SA elf (L1), ML 12, INT 1, TT as host, xp 6, spawned from it will search for a host, creating a Ge-hul in 10 Turns. The wight-worm becomes a new body organ that alters the host.
DA: life drain, infestation
ML: 12 (2 sunlight)