I used this entity against James Paterson in a new World of Darkness conversion of "The Dark Child" which, I believe, can be found in the Cthulhu Britannica books. I hedge my bets when I say that because it's been several months since I ran it. Since James was alone and didn't have much in the way of armaments, I played it more like an environmental obstacle. Despite being a vampire at the time, he nearly died and was only saved because its summoning demanded that it avoid leaving a certain (rather small) radius of the house. Bear that in mind when fielding this in World of Darkness. Cthulhoid monsters are meant to be very tough and very scary. This certainly manages to be both.
The Dark Young are greater (yet less sentient) splinters of the idigam, Shub-Niggurath, which can materialise and become fully corporeal in the real world. This is why the Dark Young haven't been discovered in our world despite our dwindling woods - they exist mostly in the Hisil. They are still potent and terrifying beings, however, whose mere presence can force you to flee in terror. They appear much like trees yet their ropy branches writh and thrash and their bark-like hide splits to reveal gaping mouths with gnashing teeth that drools green sap whose trunks function as short legs yet they smell lie the charnel house. They are also quite thick for their height - generally only reaching between 12 and 20 feet high. Among its ropy branches it possesses four ropy sinuous tentacles which it uses to attack up to four different targets in a round. These can strike or grapple their foes or it might trample a victim with its massive hooves. It makes hooting and bellowing sounds.
Rank 4 Spirit
Power 9, Finesse 3, Resistance 15. Essence 25. Defense: 15. Size: 12. Health: 27. Initiative: 18. Speed: 13 (Species Factor 1).
Numina: Ban of Power. Ban of Power. Camouflage
(look like tree). Chorus (commune with other Dark Young).
Fearstruck (instinctively cast on all viewers).
Gauntlet Breach (allows it to cross the gauntlet whenever it pleases).
Materialise (becomes solid in our world).
Stalwart (harder to damage). Elemental Immunity (Fire, Acid, Electricity). Multi-Attack (May spend essence to gain additional attacks up to four attacks that each use Power as their dice pool and must be used against creatures on the same plane of existence - mundane world, Hisil, Twilight - these manifest as tentacles). Knockdown Attack (May spend a point of essence and roll a resisted Power versus Strength or Power to knock down an opponent who is on the same plane of existence using the Trampling Hooves attack - if the Dark Young fails this roll then the target still takes damage but isn't knocked prone).
Trampling Hooves +5B (14 dice - Power with a +5 bonus due to size)
Tentacles +1L (10 dice, may grapple for 9 dice)