Ethereal Awareness. The shadow mastiff can see ethereal creatures and objects.

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.

Terrifying Howl (Recharge). The shadow mastiff howls. Any Beast or Humanoid within 300 feet of it must succeed on a DC 11 Wisdom saving throw or be frightened of it for 1 minute. A frightened target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a target's save is successful or the effect ends for it, the target is immune to any shadow mastiff's Terrifying Howl for the next 24 hours.

Shadow Blend. While in dim light or darkness, the shadow mastiff becomes 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.