Echolocation. The werebat can't use its blindsight while deafened. Keen Hearing and Smell. The werebat has advantage on Wisdom (Perception) checks that rely on hearing or smell. Hunter. The werebat rolls attacks with advantage against creatures who are frightened by it.
Multiattack. The werebat makes up to two attacks: one with its bite, or two with its claws. (This does not stack with extra attack.) Blooddrinker Bite. Melee Weapon Attack: +4 to hit, reach 5 ft, one target. Hit: 8 (1d10 + 2) piercing damage, plus 6 (1d10) necrotic damage. The werebat heals by half the amount of necrotic damage dealt, rounded down. If the target is a humanoid, it must succeed on a DC 13 Constitution saving throw or be cursed with werebat lycanthropy. Claws. Melee Weapon Attack: +4 to hit, reach 5 ft, one target. Hit: 7 (2d4 + 2) slashing damage. If the target is a humanoid, it must succeed on a DC 13 Constitution saving throw or contract Sanguinare Vampiris. Screech. Uses its action to screech, forcing each creature of its choice within 30 feet of it to make the Wisdom saving throw (DC equal to 12 + Charisma modifier). On a failed save, a target takes 7 (2d6) psychic damage and becomes frightened for 1 minute. If the frightened target takes any damage, it can repeat the saving throw, ending the effect on itself on a success.