Distraction. While in the same space as another creature, the swarm hinders the creature's attacks and spells. The creature must make a DC 14 Wisdom saving throw or have disadvantage on attack rolls and ability checks until the end of its next turn. Swarm. The swarm can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for a Medium bugbear. The swarm can't regain hit points or gain temporary hit points. It takes half damage from all attacks that use an attack roll, and double damage from all attacks that require a saving throw.
Army of Mallets. At the start of the Armies turn, any creature sharing a space or adjacent to the Bugbear Army automatically takes 22 ( 4d10 ) slashing damage or 11 ( 2d10 ) if the swarm is at half its starting hit points.
Steading of the Hill Giant Chief