Blink Dog: Hound of the Wyld Hunt

Keen Hearing and Smell. The dog has advantage on Wisdom (Perception) checks that rely on hearing or smell. 

Tracking Scent: The dog is able to track a known scent and can do so moving at speed. It has advantage to Survival checks for Hunting prey.

True Sight: The Wyld Hunt bestows the ability to see Fey in its' True Forms, thus the Blink Dogs can see through the many guises used by evil Fey.

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 5 (1d8 + 1) piercing damage. The target must make a Strength saving throw vs. DC13 or be dragged to the ground and suffer the Prone condition.

Teleport (Recharge 3–6). The dog magically teleports, along with any equipment it is wearing or carrying, up to 40 feet to an unoccupied space it can see. Before or after teleporting, the dog can make one bite attack.

Pack Tactics: When hunting as a pack, Blink Dogs can harry prey and attempt to drag them to the ground. When another Blink Dog or an ally is within 5ft of its' target the Blink Dog gains advantage on its' attacks. 

Dodge Teleport: The Blink Dog can teleport from its' location to another location it can see within 20ft as a reaction to a Ranged attack that it can see. This ability does not require a recharge roll. It is a purely defensive response to an attack and the dog will instinctively teleport away from any attackers and so will not be in a position to attack directly afterwards.