So it turns out that catoblepas comes to us by way of Latin catōblepās from Ancient Greek katôbleps or katôblepon, and its plural in Latin is catōblepae, while its Ancient Greek plural is either katôblepes or katôblepones. Of all these, I like “catoblepes” best—much more than “catoblepases.” I’m going with it. Also, the accent is on the o: ca-toh-bleh-pahs, ca-toh-bleh-peez. And that’s one to grow on!
The catoblepas is largely a scavenger, whose loathsome presence befouls the environment around it; I guess it likes its food somewhat pre-decomposed. The foul-tempered monstrosity extends this preference to any edible trespasser who wanders into its territory—thus its Death Ray feature, which inflicts considerable necrotic damage on its target, enough to kill even a level 2 or 3 player character on a successful Constitution saving throw.
Catoblepes are classified as monstrosities, but they’re unaligned and have only beast-level Intelligence, around the level of a cat or dog. Their Strength and Constitution, however, are extraordinary, and their Dexterity is above-average as well. Their darkvision suggests that they’re crepuscular and/or nocturnal; you’re not likely to run across one in broad daylight. They combine above-average passive Perception with Keen Smell, giving them an effective passive Perception of 17 if you’re upwind of them.
And you don’t want to be downwind of them. The catoblepas’s Stench feature causes everyone within 10 feet who fails a Constitution save to be poisoned—I interpret this as uncontrollable retching—imposing disadvantage on all attacks and skill checks until the start of their next turn. (A successful save means the character has acclimated to the Stench and is no longer bothered by it.)
The catoblepas’s behavior isn’t complex. When it detects a trespasser, either by sight or by smell, it starts howling and bellowing and makes straight for him or her. As soon as it comes within 30 feet, it uses its Death Ray on the first interloper it sees. From this point on, it will attack that opponent and only that opponent until he or she is unconscious or dead. If the catoblepas’s Death Ray recharges during this time, it will use it again on the same target. If not, it will whomp that target with its club-like tail.
Once it’s dispatched its prey, what it would like to do is get down to eating, but if there are other trespassers around, it would like to get rid of them first. So it will charge the next-closest enemy and continue to attack in the same way—Death Ray if it can, otherwise tail attack.
Like most evolved creatures, the catoblepas wants to survive. Unlike many, it actually has a fairly good Wisdom score, so it’s not going to wait until it’s seriously wounded to retreat. Catoblepes are formidable attackers, and any foe formidable enough to hurt them is not to be messed with further. Once a catoblepas is moderately wounded (reduced to 58 hp or fewer), it will turn tail and Dash away—unless it’s protecting its young, in which case it will Dodge and retreat at normal speed to cover its offspring’s escape. Once the young catoblepas is safely away, the parent will then turn and Dash.
Next: answering reader questions.