Shapechanger. The Blood Moon Werewolf can use its action to change between a wolf-humanoid hybrid or a large wolf. It is only able to turn back into its true form, which is humanoid, when the Blood Moon night has ended or dies. Unlike normal werewolves, the curse of the Blood Moon ignites a bloodlust that cannot be controlled. Due to the rarity and curse of the Blood Moon, the AC and stats are increased when transformed. Any items and equipment that were carried or worn on the creature before transformation does not transform with it and is either destroyed or unequipped. 

Keen Senses: While in the werewolf state, the creature's senses of sight, smell, and hearing are peeked. They get advantage on Wisdom (Perception) checks that rely on these senses for detection.

Pack Tactics: Blood Moon Werewolves have advantage on attack rolls against a creature if at least one of their allies is within 15 feet of the creature and isn't incapacitated.

Bloodlust: When a creature is dropped to 0 hit points by the Blood Moon Werewolf, the werewolf is sent into a blood frenzy. While in this frenzy, the werewolf gains advantage on melee attack rolls, and it must attack the nearest creature each turn.

Blood Scent: Upon the overwhelming scent of carnage, Blood Moon Werewolves gain an advantage against any creature that is bloodied.

Thrill of the Chase: When moving toward a bloodied target, the werewolf feels a burst of adrenaline, and moves at three times its normal speed towards their target. They can only get this rush, while under the curse of the Blood Moon's Light.

Blood Rage: When the creature loses an ally, a blinding rage fuels the Accursed Blood Moon Werewolves which boosts their attack by 14 (3d8) to their base attack die.

Multiattack. The Blood Moon Werewolf is able to perform three attacks: One bite attack and two claws attack.

Claws. Melee Weapon Attack: +14 to hit, reach 5 ft., one target. Hit: 27 (6d8 + 4) [slashing] damage.

Bite. Melee Weapon Attack: +14 to hit, reach 5 ft., one target. Hit: 45 (9d8 + 4) [piercing] damage. If the target is humanoid, it must succeed on a DC18 Constitution saving throw, or be cursed with Blood Moon Werewolf Lycanthropy.

Alpha's Howl (Recharge 4-6). The werewolf lets out a loud bone-chilling howl. Each enemy within 60 feet of the werewolf must make a DC18 Wisdom Saving Throw. On a failure, the creature takes 54 (12d8) psychic damage and becomes Frightened of the werewolf until the end of their next turn, taking only half the damage on a success.

Vengeful Strike. While the werewolf is in the blood frenzied state and is attacked by a creature, it makes a claw attack reaction. If it hits the target, they take an additional 14 (3d8) damage on top of the normal claw damage.

The Accursed Blood Moon Werewolf can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature’s turn. The creature regains spent legendary actions at the start of its turn.

Claws. The creature makes its Claws attack once.

Bite. The creature makes its Bite attack. It cannot be used with the Cursed Frenzy Action.

Bloodbath (Costs 2 Action). The enhanced Blood Moon Werewolf can unleash its Alpha's Howl and three Claws attack on the nearest target.

Cursed Frenzy (Costs 3 Actions). The Accursed Blood Moon Werewolf is fueled from the powerful carnage. The monstrosity makes a Bite attack. The Bite is automatically a critical hit, and if the target is humanoid, it must succeed on a DC25 Constitution saving throw, or be cursed with Blood Moon Werewolf Lycanthropy. It then draws on the lifeforce of the bite and regains Hit Points worth half of the total amount of damage it produces.