Multiattack

The rat king makes two Bite attacks.

Bite

Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) piercing damage plus 7 (2d6) poison damage. If the target is a creature, it must succeed on a DC 14 Constitution saving throw or suffer one level of exhaustion and become infected with a disease. Until the disease is cured, at the end of each long rest, the creature must repeat the saving throw. On a failure, the creature suffers another level of exhaustion. The exhaustion lasts until the creature finishes a long rest after the disease is cured. A creature that succeeds on two saving throws recovers from the disease.

Call Rats (1/Day)

The rat king magically calls 2d4 rats, 1d4 giant rats, or 1 swarm of rats. The rats arrive in 1d4 rounds, acting as allies of the rat king and obeying its spoken commands. The rats remain for 1 hour, until the rat king dies, or until the rat king dismisses them as a bonus action.