Armor Class 14 (natural armor)
Hit Points 84 (8d10 + 40)
Speed 30 ft.
Senses darkvision 60 ft., passive Perception 12
Languages —
Challenge 5
Keen Smell. The catoblepas has advantage on Wisdom (Perception) checks that rely on smell.
Stench. Any creature other than a catoblepas that starts its turn within 10 feet of the catoblepas must succeed on a DC 16 Constitution saving throw or be poisoned until the start of the creature's next turn. On a successful saving throw, the creature is immune to the stench of any catoblepas for 1 hour.
Tail. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 21 (5d6 + 4) bludgeoning damage, and the target must succeed on a DC 16 Constitution saving throw or be stunned until the start of the catoblepas's next turn.
Death Ray (Recharge 5–6). The catoblepas targets a creature that it can see within 30 feet of it. The target must make a DC 16 Constitution saving throw, taking 36 (8d8) necrotic damage on a failed save, or half as much damage on a successful one. If the saving throw fails by 5 or more, the target instead takes 64 necrotic damage. The target dies if reduced to 0 hit points by this ray.
Volo's Guide to Monsters, p. 129