Swarm. The swarm can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for a Tiny book. The swarm can't regain hit points or gain temporary hit points. False Appearance. While the swarm remains motionless, it is indistinguishable from an inanimate pile of books.
Slam. Melee Weapon Attack: +4 to hit, reach 0 ft., one creature in the swarm's space. Hit: 5 (2d4) bludgeoning damage, or 2 (1d4) bludgeoning damage if the swarm has half of its hit points or fewer.