Black Shuck

Blood Frenzy. Has advantage on attack rolls vs. any creature that doesn't have all its hp.

Keen Hearing and Smell. Has advantage on Wis (Perception) checks that rely on hearing or smell.

Water Walker. Can move across the surface of water as if it were harmless solid ground. This otherwise works like the water walk spell.

Multiattack. Three Bites and can use Curse of the Grave or Fearsome Howl if available. If 2+ Bites hit a Med or smaller target black shuck sinks in its teeth shaking head violently. Target: DC 17 Str save or 7 (2d6) slashing damage and be thrown up to 15 ft. in random direction and knocked prone.

Bite. Melee Weapon Attack: +8 to hit, 5 ft., one target, 13 (2d8+4) piercing damage and 10 (3d6) necrotic.

Curse of the Grave. Glares at one creature it can see within 30' of it. Target: DC 17 Wis save or be cursed: disadvantage on next two death saves it makes in the next 7 days. Curse lasts until cursed creature has made two death saves until 7 days have passed or until it is lifted by a remove curse spell or similar magic.

Fearsome Howl (Recharge 5-6). Howls a haunting tune. Each creature within 60' and can hear it: frightened until the end of its next turn (DC 17 Wis negates). A frightened creature concentrating on a spell must make DC 17 Con save or it loses concentration.

Mist Stalker. In dim light fog or mist it takes the Hide action.