Barghest

Barghests are lupine outsiders that exist to spread fear and feed upon humanoid heroes. Cunning and disciplined but utterly self-centered hunters, barghests shun chaos. However, legend says the goddess of monsters, Lamashtu, freed the first barghests from the kennels of Hell. The greatest among them still live in a section of the Abyss they claim as their territory. Goblin belief holds that the strongest of these barghests helped create goblinkind in time immemorial. Evil goblins, therefore, revere barghests as wicked hero-gods.
These fiends hunt and kill good-hearted humanoids to feed on the spiritual energy left within the corpses of such foes. Although a barghest might slay the innocent or weak, and even eat such prey, it gains the growth-inducing nourishment it seeks only from worthy opponents. Barghests commit atrocities to attract the attention of such would-be champions before murdering and devouring them, growing in size, magical power, and social standing with each success.
Masters of deception, barghests can transform into goblinoids or wolves at will. They use such forms to remain beneath notice to travel incognito or until ready to pounce. A typical barghest is 6 feet long and weighs 200 pounds. When it gains power, a barghest also gains size. The mightiest among them are twice the size of their lesser kin.