Source: Bestiary 6, pg(s). 180
In its true form, a Leng hound resembles a corpselike hunchbacked humanoid covered in fur, with clawed hands and paws, bat wings and a partially canine face. It is seven feet tall but weighs only 150 pounds. It is capable of retracting its bestial features: fur and wings retract, the skin covering them slithers into hidden cavities and jaws pull back to a human face. Leng hounds prefer to lurk inside the coffins they guard, rearranging their bodies into skeletal shapes.
On their home plane, Leng hounds haunt its unimaginably old ruins and roam the desolate tableland in search for prey to bring to their masters. They eagerly accept being summoned to the Material Plane to serve as guards of graves containing the corpse of evil creatures, in exchange for the opportunity to feast upon other corpses in the cemetery. If a creature disturbs or loots this grave, the Leng hound can track the looters or looted goods across the universe, and emits a deep, sardonic howl that only the thieves can hear.