There’s a creature in D&D called the ‘Intellect Devourer’. It’s essentially a big brain on legs. In terms of challenge levels, the Intellect Devourer is fairly flimsy on it’s own. Yet it also has an ability that causes permadeath.
The intellect devourer initiates an Intelligence contest with an incapacitated humanoid within 5 feet of it. If it wins the contest, the intellect devourer magically consumes the target’s brain, teleports into the target’s skull, and takes control of the target’s body.Monster Manual
Usually when you’re knocked out in battle, you get to roll to avoid death, and if you fail, a healer might bring you back. The lowly Devourer eats your brain before any of that happens.
The Pogrebin has the same energy. A small critter that could easily be dispatched, but with a potentially character-ending ability. All it needs is a little time.
This is not a critter to use in any meaningful way in combat. Even against a level 1 party, the pogrebin will be squished pretty quickly. No, this is a monster that adds a threat during downtime.
Imagine: the party stumbles out of a tavern after celebrating their most recent, successful adventure. Drunk and exhausted, they fail to notice the stone that shifts from the side of the dirt road and crawls after them, and when one of them begins to feel depressed as they continue the pub crawl, they may simply pass it off as the effects of alcohol. If they don’t suspect anything, it may be the end for that adventurer. Alone in their tavern room, the despair takes over and they collapse. The pogrebin crawls in through the open window, ready to ‘completely devour’ the prey.
Alternatively, this could be a quest in itself. Lonely townsfolk have vanished in the dead of night, leaving nothing but streaks of blood. There doors were locked, no one was seen anywhere near the scene. All anyone knows is that the last time they saw the victim, they seemed unusually crestfallen…
Remember that a ‘commoner’ has four hit points, and a flat roll when they make a wisdom saving throw. So if a pogrebin is in town, and no one spots them, things could get very horrifying very quickly.
Thank You For Reading
The rest of the Fantastic Beasts as Dungeons & Dragons monsters can be found here.