Keen Hearing and Smell. The dog has advantage on Wisdom (Perception) checks that rely on hearing or smell.
Actions
Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 4 (1d6 + 1) piercing damage.
Teleport (Recharge 4-6). 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.
RollQuest summary Senses: passive Perception 13. Languages: Blink Dog, understands Sylvan but can't speak it. Skills: Perception +3, Stealth +5. Speed: 40 ft.
RollQuest ships the D&D 2014 SRD as a content pack, on a 5e character sheet that does the maths - roll from the sheet and let the numbers work themselves out. Free to start.