You know what fifth edition D&D doesn’t have and desperately needs? A catoblepas. YOUR WELCOME.
Large monstrosity, unaligned
Armour Class 16 (natural armour)
Hit Points 200 (16d12 + 96)
Speed 40 ft., swim 20 ft.
STR 20 (+0) DEX 8 (-2) CON 22 (+6)
INT 5 (+0) WIS 11 (+0) CHA 11 (+0)
Skills Perception + 11
Senses darkvision 60ft., passive Perception 10
Challenge 13 (10,000 XP)
Amphibious. The catoblepas can breathe air and water.
Raven Queen’s Presence. Any creature within 30 feet has disadvantage on death saving throw.
Multiattack. The catoblepas makes three attacks: one with its gore and two with its tail.
Gore. Melee Weapon Attack: +11 to hit, reach 10ft., one target.
Hit: 17 (2d10 + 6) piercing damage plus 4 (1d8) poison damage.
Tail. Melee Weapon Attack: +11 to hit, reach 15ft., one target.
Hit: 15 (2d8 + 6) bludgeoning damage.
Poison Breath (Recharge 5-6). A catoblepas’s horrid, stinking breath is 60-foot cone of poison gas. Each creature in that area must make a DC 17 Constitution saving throw, taking 56 (16d6) poison damage on a failed save and gaining the poison status effect, or half as much damage and no poison status affect on a successful one.
Final Glance. Whenever an attack of opportunity is triggered instead of making a melee attack the catoblepas may use final glance instead. The triggering enemy must make a DC 17 Wisdom or Intelligence saving throw or take 24 (8d6) necrotic damage and become immobilized and gains vulnerability against all damage (save ends both).
This ugly creature has a boar-like head with short antlers, a thick bullish body covered in spines, and cloven hooves on its stumpy legs.