Way back in the day when 2E was all the rage, I was GMing a group through some homebrew adventure where they had to infiltrate a castle, kill the bad guys, save the princess, get the kewl lewt, etc. They get to the final boss battle, taking place in a large dining hall. It's your standard group - fighter, mage, thief, cleric, with a bard thrown in for good measure because Jeff had the rolls for it and he liked bards and even though I hate them he HAD to play one - and they aren't doing all that bad. The bad guys start to get the upper hand, with the BBEG - a high level mage - and his 2 warrior assistants starting to pummel the group. It's a back and forth affair to this point, and everyone is having fun.
But the dice gods had other plans for this fun time. I will state up front that I could have fudged this, but the outcome was so insane that as a group we decided to let it stand. And yes, it ended up in the player's favor. But it was pretty darned cool.
The BBEG is in the back, with a warrior on either side diagonally so they are standing in a 5 ft triangle. The mage casts fireball at the players, and they take some serious damage. The bard is nearly unconscious, the mage is unconscious, and the cleric is about out of healing spells. So one of the BBEG's warrior bodyguards goes, stepping forth and swinging his sword at the PC thief. Natural 1. This is at the time where the random critical fail tables were all the rage, and we were using them. So a natural 1....roll the d100...and the sword goes flying out of his hand. So I check direction...and it's aiming right for the rope that happens to hold the chandelier the bad guys are standing under.
I'm sure you can all guess what happens next.
I roll an attack for the sword, and thwick! The rope gets cut and the chandelier comes crashing down. So I'm off to check DEX checks...and all 3 of the enemies fail. In fact, the BBEG mage rolls a natural 20 on that DEX check, which is a critical failure. They all get trapped under the chandelier, with the BBEG mage actually getting killed by crushing damage from it. The enemy warriors were rather injured, one knocked cold. Our thief, who happens to not be good, performs the coup de grace on the warriors, and it's game over.