Reminds me of a story I heard from back in the 2e days when the group was fleeing a dungeon, low on resources, and ran into the vampire lord's son at the far end of a 100' long, 6' tall hallway.
The group groaned and looked at their sheets, trying to figure out how they were going to get out of it alive.
The archer in the group said "if I break the tip off of one of my arrows, can it be like a stake if I hit it in the heart?"
The DM thought about it for a moment and said "yes, but with the broken shaft, low ceiling, poor light, and distance to the target you need to roll two 20s in a row to make the shot."
The table went silent as the archer's player stood up and began shaking his dice. Roll: 20.
A cheer goes up, but he's still go to roll another 20. He picks up his dice and everyone stands up, unable to sit with the tension around that roll. He rolls it, they lean in, and... 20!
The vampire lord's son explodes in a flurry of ash and the group limps out of the dungeon (to talk about it years later around the table and eventually to be spread elsewhere).
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The closest I've come as a player in DnD is when our 4e group was at the depths of an abandoned dwarven fortress (based on
Boatmurdered) and ran into Sankis the flaming ghost that had been randomly popping out of walls, punching people with a laugh, then disappearing.
He rose out of a pool of magma, starting to deliver a rambling, insane speech when my Ranger rolled initiative. He moved up, used Armor Splinter to drop his AC(critting with one attack and getting a free one from Two-Weapon Opening), then unleashed Blade Cascade, critting on two of the attacks(each giving him another Basic Attack). The elite died in one round to a flurry of 8 attacks, three of which were crits in the 70-90hp range(Level 15) - and I still had two attacks left in my Blade Cascade that I didn't get to use!