Ningyo

The ningyo can breathe only underwater and can hold its breath for 1 hour.

When a creature that the ningyo can see attacks the ningyo and misses, the attack is automatically redirected against another creature within 5 feet of the ningyo or the attacker. This attack uses the same attack roll.

The ningyo makes four barbed tentacle attacks.

Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 8 (1d6 + 5) piercing damage plus 5 (1d10) poison damage.

When the ningyo takes damage, it can choose to take half the damage instead. The ningyo then chooses a creature within 60 feet. The target must succeed on a DC 15 Constitution saving throw or have disadvantage until the end of its next turn as it is wracked with the pain of the attack.