Echolocation. The swarm can’t use its blindsight while deafened.
Keen Hearing. The swarm has advantage on Wisdom (Perception) checks that rely on hearing.
Dark Devotion. The swarm has advantage on saving throws against being charmed or frightened.
Blood Frenzy. The swarm has advantage on melee attack rolls against any creature that doesn't have all its hit points.
Swarm. The swarm can occupy another creature’s space and vice versa, and the swarm can move through any opening large enough for a Tiny bat. The swarm can’t regain hit points or gain temporary hit points.
Domain Misty Escape. When it drops to 0 hit points outside its resting place, the swarm transforms into a cloud of smoky mist instead of falling unconscious, provided that it is within its masters domain. If it can’t transform, it is destroyed. While it has 0 hit points in mist form, it can’t revert to its bat form, and it must reach its resting place within 2 hours or be destroyed. Once in its resting place, it reverts to its bat form. It is then paralyzed until it regains at least 1 hit point. After spending 1 hour in its resting place with 0 hit points, it regains 1 hit point.
Bite. Melee Weapon Attack: +4 to hit, reach 0 ft., one creature in the swarm's space. Hit: 5 (2d4) piercing damage, or 2 (1d4) piercing damage if the swarm has half of its hit points or fewer.
Blood Drain (Recharge 6). After a hit on a creature the swarm attaches to the creature biting at main blood vessels, the creature loses 9 (2d4 + 4) hit points due to blood loss.
Sonic Screech. The swarm screeches out a high pitch horrific noise that almost sounds like blood curdling screams. Each creature within a 10ft radius center on the swarm must make a DC 12 Constitution saving throw, taking 3 (1d6) psychic damage and has disadvantage on their next ability check/attack on a failed save, or half as much damage and no disadvantage on a successful one. Each creature within 20ft of the swarm that can hear its screeches a must succeed on a DC 12 Wisdom saving throw or become frightened until the end of the swarm's next turn. If a creature's saving throw is successful, the creature is immune to this swarm's screech for the next 24 hours.
Seek Blood. As a reaction action, the swarm can move up to its speed toward a hostile creature that it can see.
Description
The vampire has many of familiars to protect its domain and the bats are among the most useful. Vampire Familiar (Swarm of Bats) appear to be normal bats from a far but when they get closer the pale red eyes leave trails as they swoop to swarm a creature. Their teeth are long and thin almost like a long, needle-like proboscis. Their wings and feet have sharp pincers to help them latch onto their targets.
These bats are more furious than regular since they know if they are destroy they will return to their place of rest within their master's domain. Unless ordered to kill, their main duties are to roam their master's domain to be spies.