The Hungry Jelly
I’m one of those DM’s who lets you roll on a critical fumble table when you roll a natural 1. I think it’s just fair if you consider the huge impact a natural 20 brings. Moreover there’s no thing as “automatic success” in my campaigns (the spellcasters even have to roll for a cantrip).
My party consisted of a Half-Elf Bard, a Human Fighter, and a Half-Elf Warlock. They called themselves “Two half and a man.” Their very first quest was a classical adventure that took them underneath the village of Daggerfall. After a few encounters that happened to be no real match for the group, they found a stinking hole. It seemed to be a dungeon garbage pit that could (or could not) contain some treasure.
On the very bottom of the pit (8 or 10 feet below) was a slimy monster, some kind of Ochre Jelly which stretched its pseudopods towards the group without reaching them. The Bard and the Fighter—realizing they were just level 2—didn’t find the risk worth the reward and wanted to move on.
Not so the Warlock. Looking at his character sheet he said, “No problem, guys! I can shoot Eldritch Blast from a safe distance. And because it’s a cantrip I can shoot as many as it takes to vaporize that son of a pit!”
The Bard and the Fighter saw no sense in that attack, but the Warlock’s player was a real munchkin and wouldn’t leave any possible treasure behind.
As he stepped towards the edge of the pit I warned him. “Remember, you have to roll for every single attack. The monster isn’t hard to hit, but when you fumble, you’ll just fall into the pit!”
Warlock smiled, winked, and rolled his D20. Natural 1.
While all three players burst into laughter, I began to roll. The falling damage already brought the Warlock’s HP to the single digits. One pseudopod hit later he was knocked unconscious (even before the additional acid damage).
The Fighter started to climb down the pit, but the Jelly fiercely protected the snack he’d be waiting for for so long. One round later the Warlock was dead. The Bard and the Fighter just shrugged their shoulders.
“Well, that was unnecessary, but not undeserved.”