This is a very recent story, of a campaign I started playing a few weeks ago. The campaign is a very atypical Dungeons and Dragons campaign, with dashes of Big Eyes, Small Mouth (also known as the roleplaying system for anime fans) and of d20 Modern. The setting is very strange: there's an empire that threatens to dominate the world, but instead of with swords and bows, they do with rifles and firearms, which only people from the Empire are trained enough to use. Our characters are facing very tough odds, but that is not enough. The dungeon master is quite fond of videogames, and decided to add some very tough "Generals" to the campaign. Namely, he added Cloud, Sephiroth, Mega Man X, and Zero as generals of the army, adapting them to the D&D world. The adventuring party is composed of a human fighter (a maniac with a greatsword), 3 human paladins (yes, three human paladins) including my character, who's from the heretic Lawful Good sect of the imperial religion (which is Lawful Evil, and hell-bent on our extinction), a 4000-year old guy from a forgotten era (who also belongs to my religion), and a noble-bred paladin who quests for justice and righteousness. An Elven monk had also joined recently.
The thing that happened was the following: we were escaping from one of the Imperial bases, and managed to get a lift from a merchant's Airship (eerily reminiscent of the RE4 merchant, up to the point of treating everyone as "Strangers..."), who unfortunately perished by Sephiroth's son (who just happens to be Kadaj from the Advent Children movie). After the escape, we went to a city that the merchant had mentioned to the fighter before, only to find it in ruins because they allowed the merchant's guild of said merchant and the heretic sect to have bases there. We eventually had to negotiate to get (actually, to recover) some Chocobos, in order to reach a secret temple of the Heretics, and save them from the Imperial Army. Of course, we were a bit too late, and the temple was already besieged. We entered to find Cloud getting a rare crystal for the empire and leaving us with two heavy troopers. We withdrew, finding Cloud giving the crystal to some person, and eventually facing us. However, the importance of this story isn't the fight with Cloud or the escape. The important part of the story is the chain of events that concluded in the unbelievable conclusion, something even the dungeon master wasn't expecting.
Before entering the castle, the dungeon master gave us some time to rest and eat before fighting. I had no rations, so I just said my character was fasting to ensure our victory. The dungeon master then gave me a bonus on the check to ask for God's divine intervention (yes, God, the Lord). That was the beginning of the dungeon master's nightmare. When Cloud got the crystal he was looking for, I told the dungeon master I wanted to ask for his intervention, smiting Cloud in the process. The dungeon master allowed me the roll, and eventually Cloud got smote by a flash of light, which apparently did nothing to him. Then, in the battle against the troopers, no one did even a bit of damage except me, who managed to disarm one of the soldiers of his tower shield, and struck a few blows. The divine intervention, however, did not stopped there...
After retreating from the seemingly invincible guards, we went up and faced a washed-down version of Cloud (a story battle, in which after he had a few HP left, he'd retreat). Cloud had managed to have the upper hand in the beginning, as expected. When I drew my longsword and attacked him, the dungeon master said that the sword struck right on the wound where God smote Cloud. Nothing unusual, just something fancy of his part. Then, the 4000-year old paladin drew his lance, and also struck the enemy. The DM allowed him to roll a percentile dice, just to see if the lance landed on the wound too. The guy rolled a 0 and a 00, which means he rolled a 100% chance. Thus, the DM had to accept that the lance landed right where my sword was, further weakening Cloud (reducing his attack bonus and AC, and also forcing him not to move). Then, when everybody (especially the 3 paladins...) was on range, the paladins decided to reduce their Initiative modifiers to make a combined Smite Evil attempt. At the moment, Cloud was attempting to remove the sword and the lance, but to no avail. Also, at that moment, the dungeon was so amazed by our darned luck that he was about to let Cloud go away.
Then, the unexpected happened. 2 of the 3 paladins missed their smite evil attempts, mine being the only one succeding. Soon after, the DM said that, regardless of the losses, they managed to strike Cloud (with a 6 or so in the attack roll, and being lvs. 1~2...). Then the fighter wanted to attack Cloud, since it would mean an automatic hit.
The fighter rolled to check if he hit Cloud. He rolled a natural 20--a critical hit. Since he knew he'd strike anyways, he consumed all of his base attack bonus on the Power Attack feat, which allowed him to subtract points from the BAB, and add them to the damage dealt. Since he held a weapon with two hands, his Strength bonus plus his Power Attack bonus was multiplied by 1.5 times. The greatsword he held, according to the DM, was sharpened to hold a razor edge (a house rule he invented), that gave the sword an extra 1d4 of damage, besides the 2d6 of damage the sword deals normally. Since the hits would land automatically, the critical threat because of the natural 20 was confirmed, and the damage would be doubled. he rolled a 4 on the d4, and a 5 and 6 on the d6s. The whole damage to Cloud, on one turn, was over 50 hp of damage. At that moment, the DM stopped the battle, and changed the whole course of the story...
The combined smite, the 100% roll on the percentile dice, the divine intervention roll, and the fighter's critical hit made him say that a "wave of positive energy exploded..." That meant the following: we had defeated Cloud automatically, we had purified Cloud from his evil condition, Cloud stopped a dangerous weapon from firing by sticking his sword on the cannon, and the event produced a massive blast of purifying energy that acted like a massive Atonement spell, making all people in the area Lawful Good (Cloud, the non-LG adventurers, the soldiers, and everything in a 5-mile radius). That means we had converted a crack squad of destruction into our faithful followers, and in only one round, with one very lucky move.
Thus, what the DM thought was a simple request from a Paladin to God became the most amazing act of Divine Intervention in many campaigns worldwide.