Swarm of Infesting Insects

The swarm can occupy another creature's space and vice versa, and it can move through any opening large enough for a Tiny creature. The swarm can't regain Hit Points or gain Temporary Hit Points.

Melee Attack Roll: +4, reach 5 ft. Hit: 12 (4d4 + 2) Poison damage, or 7 (2d4 + 2) Poison damage if the swarm is Bloodied, and the target has the Poisoned condition. If the target remains Poisoned in this way after 1 hour, it is subjected to the following effect. Constitution Saving Throw: DC 11. Failure: Roll 1d6: on a 1-2, the target has the Blinded condition; on a 3-4, the target's Hit Point maximum decreases by 5 (1d10); on a 5-6, the target gains 1 Exhaustion level. The effect lasts until the Poisoned condition ends. Success: The Poisoned condition ends.