Foul Stench. Any creature that starts its turn within 10 feet of the athach must succeed on a DC 16 or be poisoned until the start of its next turn. On a successful saving throw, the creature is immune to the athach's stench for the next 24 hours.
Multiattack. The athach makes four attacks: three with its clubs and one with its bite.
Bite. Melee Weapon Attack: +8 to hit, reach 5 ft., one creature. Hit: 12 (3d4 + 5) piercing damage, and the target must succeed on a DC 16 Constitution saving throw or be poisoned for 1 minute and unconscious while poisoned in this way. The target wakes up if it takes damage or if another creature takes an action to shake it awake.
Club. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 12 (3d4 + 5) bludgeoning damage.
Rock. Ranged Weapon Attack: +8 to hit, range 60/240 ft., one target. Hit: 21 (3d10 + 5) bludgeoning damage.