Reaper Bat

Source: Harker's Guide to Vampire Hunting

Reaper bats are relentless carnivorous hunters that are unafraid to take on much larger and tougher prey than typical bats. While a single reaper bat poses little to no threat to a typical adventurer, they communicate with one another using their echolocation, eventually creating large swarms that can overwhelm the unsuspecting hero.

Reaper Bat
Monster Level: 0.5
Diminutive. Beast
STR	DEX	END	AWR	INT	CHA
-3	1	0	3	-3	-2
	Ref: 11	Fort: 10	Ant: 13	Log: 7	Will: -2
Armor Rating 10			Vulnerable Radiant 1, Sonic 3
Hit Points 2			Senses Blindsight 60 ft (cannot see beyond this point)
Speed 5 ft, Fly 30 ft			Traits Vigilant
Skills (AWR) Perceiving +4, Tracking +4
Features
Echolocation. The Reaper Bat can see any source of moderate to loud noise (the volume of normal conversation or louder) within 1000 ft of it, ignoring its Blindness from Blindsight. Echocommunication. The Reaper Bat is aware of everything that other Reaper Bats within 60 ft of it can see using their Blindsight.
Actions
On each of the Reaper Bat’s turns, it may take one of the following sets of actions. Move, take one Tier 1 action, and take one Tier 2 action, if available.
Tier 1 Actions
Move. The Reaper Bat can move up to its speed. Bite. Reach 5 ft Natural Weapon. +1 vs AR. Hit: 2 (1d2+1) sharp.
Tier 2 Actions
Squeaking Summons (Recharge 6). The Reaper Bat summons another Reaper Bat that appears in an unoccupied space within 60 ft of it. The new Reaper Bat rolls its own Initiative and acts on its own turn.