Cloud of Insects

Swarm. The cloud can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for a Tiny insect. The swarm can't regain hit points or gain temporary hit points.

Slow. The cloud cannot take the Dash action, and cannot make Opportunity Attacks.

Hefty Eaters. The cloud will always try to encompass as many creatures inside of its space as it can, and will always move to do so. In the case of all nearby creatures being too far spread out, it will instead target the heartiest looking creature it can reach.

Hydrophobic. The cloud cannot swim, and will avoid water if possible.

Short Attention Span. The cloud will lose interest in any creature it cannot envelope within itself if that creature avoids it for at least 1 minute.

Multiattack. The cloud makes two attacks: one with its bite and one with its sting.

Bite. Melee Weapon Attack: +3 to hit, reach 0 ft., all targets in the cloud's space. Hit: 5 (2d4) piercing damage, or 3 (1d4) piercing damage if the swarm has half of its hit points or fewer.

Sting. Melee Weapon Attack: +3 to hit, reach 0 ft., one target in the cloud's space. Hit: 4 (1d6) poison damage.