Koralk

Devil's Sight. Magical darkness does not impair the koralk's darkvision.

Harvester Venom. The koralk produces a potent poison that liquefies the innards of those affected by it. Every hour that elapses after a creature succumbs to this poison, it must succeed on a DC 17 Constitution saving throw or take 7 (2d6) poison damage, and its hp maximum is reduced by that amount. Creatures with resistance or immunity to poison or the poisoned condition can be affected by this poison. Such creatures have advantage on the saving throw.

Magic Resistance. The koralk has advantage on saving throws against spells and other magical effects.

Steadfast. The koralk can't be frightened while it can see an ally within 30 feet of it.

Multiattack. The koralk makes one Bite attack, one Scythe attack, and three Stinger attacks. It can replace its Scythe attack with a Vestigial Arms attack.

Bite. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 14 (2d8 + 5) piercing damage.

Scythe. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 16 (2d10 + 5) slashing damage.

Stinger. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 7 (1d4 + 5) piercing damage plus 7 (2d6) poison damage, and the target must succeed on a DC 17 Constitution saving throw or succumb to the devil's venom (see the Harvester Venom trait).

Vestigial Arms. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: If the target is a Medium or smaller creature, it is grappled (escape DC 17). Until this grapple ends, the creature is restrained, and the devil can't use its Vestigial Arms on another target.