Swarm, Biting Gnat 2014
CR 1/4 beast
Medium beast, unaligned
Can pinpoint by scent the location of warm-blooded creatures within 20' of it.
A creature that is not deafened and starts its turn in a space occupied by a swarm of biting gnats must make DC 10 Wis save or become distracted by the droning of the gnats’ wings. A distracted creature has disadvantage on attack rolls and ability checks that use Int Wis or Cha for 1 min. A creature can re-save at end of each of its turns success ends effect on itself. If a creature’s save is successful the creature is immune to the swarm’s Distracting Buzz for the next 10 min.
Can occupy another creature’s space and vice versa and swarm can move through any opening large enough for a Tiny beast. Can’t regain hp or gain temp hp.
Source: Tome of Beasts 3 (Kobold Press) · License: OPEN GAME LICENSE Version 1.0a details