I love hive creatures; creatures who are stronger in a group than as individuals. There are various approaches to implement the 'hivyness' and the example below does that by creating a single entity whose stats depend on the amount of creatures. By the lack of a better name, I dubbed it as the bee swarm.
The bee swarm can take up any shape, ranging from a cloud to a humanoid appearance. It is almost immune to slashing and piercing weapons (each doing only 1 dmg per hit) and also bludgeoning weapons do only half damage. It is, however, very vulnerable to fire (double damage). The bee swarm can be of any size according to the amount of bees it consists of. For every 10 hp it gains one attack. Casters who are attacked by the swarm cannot cast spells, even when the attack misses. Below 10 hp the swarm is considered to be dispersed, possibly with the bees fleeing to grow another hive swarm.
Int: Semi-Intelligent (2-4)
# Appearing: Varies
# Attacks: 1 attack/10 hp