AC 12
HP 18 (4d8; bloodied 9)
Speed 5 ft., fly 30 ft.
Proficiency +2; Maneuver DC 12
Damage Resistances bludgeoning, piercing, slashing
Condition Immunities charmed , frightened , grappled , paralyzed , petrified , prone , restrained , stunned , unconscious
Senses blindsight 60 ft., passive Perception 11
Languages —
Echolocation. The swarm can’t use blindsight while deafened .
Keen Hearing. The swarm has advantage on Perception checks that rely on hearing.
Swarm. The swarm can occupy another creature’s space and move through any opening large enough for a Tiny creature. It can’t gain hit points or temporary hit points. It becomes Medium when bloodied .
ACTIONS
Bites. Melee Weapon Attack: +4 to hit, reach 0 ft., one target. Hit: 7 (2d6) piercing damage, or 3 (1d6) piercing damage if the swarm is bloodied ..
Slicing Flurry. Each creature sharing a space with the swarm makes a DC 12 Dexterity saving throw , taking 10 (4d4) slashing damage, or 5 (2d4) slashing damage if the swarm is bloodied , on a failure, or half as much on a success. Creatures can gain advantage on this saving throw by choosing to fall prone .
Sickle bats inhabit dark corners of deep caves, swooping down from their perches to strike from above. The first fingers on a sickle bat’s wings are tipped with a small sickle shaped claw that they slice into their prey as they fly by, swarming like aerial piranhas. When one of their targets is bloodied they fall into a frenzy, focusing on that creature to the exclusion of all others.
Beasts are natural animals whose existence and abilities are nonmagical. A bear and a tyrannosaurus rex are both beasts.