Corrupted Giant Constrictor Snake

Abyssal Corruption. The snake has been infected by water corrupted by the Abyss, and has been overtaken by an unstoppable rage. It gains resistance to bludgeoning, piercing, and slashing damage from nonmagical weapons. Its proficiency bonus is added to its weapon attacks. If the creature has a bite attack, this attack deals 1d6 additional poison damage, and the target must make a Constitution saving throw (based on 8 + proficiency bonus + constitution modifier). On a failure, the target is poisoned. If the target fails by more than 5, the target is corrupted by the Abyss. See the Abyssal Corruption table in Chapter 2 of the Dungeon Master's Guide for effects the target may suffer.

Bite. Melee Weapon Attack: +6 to hit, reach 10 ft., one creature. Hit: 13 (2d6 + 6) piercing damage, as well as 3 (1d6) poison damage, and the target must make a DC 11 Constitution saving throw. On a failure, the target is poisoned, and on a failure of 5 or more, the target is corrupted by the Abyss.

Constrict. Melee Weapon Attack: +6 to hit, reach 5 ft., one creature. Hit: 15 (2d8 + 6) bludgeoning damage, and the target is grappled (escape DC 16). Until this grapple ends, the creature is restrained, and the snake can't constrict another target.