Blood Frenzy. The demogorgon has advantage on melee attack rolls against any creature that doesn't have all its hit points.   Keen Smell. The demogorgon has advantage on Wisdom (Perception) checks that rely on smell.   Regeneration. The demogorgon regains 10 hit points at the start of its turn. If the demogorgon takes acid or fire damage, this trait doesn't function at the start of the demogorgon's next turn. The demogorgon dies only if it starts its turn with 0 hit points and doesn't regenerate.