Armor Class 17 (natural armor)
Hit Points 65 (10d6 + 30)
Speed 30 ft.
Skills Stealth +6
Senses blindsight 60 ft. (blind beyond this radius), passive Perception 10
Languages —
Challenge 4
Amphibious. The serpentmaw can breathe air and water.
Pack Tactics. The serpentmaw has advantage on an attack roll against a creature if at least one of the serpentmaw's allies is within 5 feet of the creature and the ally isn't incapacitated.
Multiattack. The serpentmaw makes one Bite attack and two Claw attacks.
Bite. Melee Weapon Attack: +5 to hit, reach 15 ft., one target. Hit: 10 (2d6 + 3) piercing damage, or 17 (4d6 + 3) piercing damage if the serpentmaw had advantage on the attack roll.
Claw. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) slashing damage.
CRCotN, p. 208