Ethereal Awareness. The shadow mastiff can see ethereal creatures and objects.
Keen Hearing and Smell. The shadow mastiff has advantage on Wisdom (Perception) checks that rely on hearing or smell.
Shadow Blend. While in dim light or darkness, the shadow mastiff can use a bonus action to become invisible, along with anything it is wearing or carrying. The invisibility lasts until the shadow mastiff uses a bonus action to end it or until the shadow mastiff attacks, is in bright light, or is incapacitated.
Sunlight Weakness. While in bright light created by sunlight, the shadow mastiff has disadvantage on attack rolls, ability checks, and saving throws.
Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit:10 (2d6 + 3) piercing damage. If the target is a creature, it must succeed on a DC 13 Strength saving throw or be knocked prone.
These black hounds of the Shadowfell move invisibly through the shadows, always on the hunt. In gloomy places where the veil between the Shadowfell and the Material Plane is thinnest, they can cross over into the dark realms of the world.