The keyed zone in Velious was called Sleeper's Tomb. It housed Kerafym, the Sleeper, who was the spawn of two different colored dragons and the most powerful being to exist on Norrath. He was guarded by four warders that made sure no one would wake him up. The parts of the key to enter the tomb were entrusted to several high ranking dragons. Enter: the player.
Kalaran at this point had been banned and reborn as Furor Planedefiler, the Human Warrior. FoH did what it did best and beat the everliving shit out of the high ranking dragons, and assembled a small team of players keyed for the tomb. The inside of Sleeper's Tomb at this point was largely unfinished, from missing items to default human models instead of actual mobs, the whole place was broke dick. No one was supposed to be in there this quick, and so like anyone would expect, the whole zone fell to them, warders and all. The Sleeper spawned as a default human model, and the script for the event terminated abruptly. This script was supposed to change the entire world upon its activation, but it didn't even change the inside of Sleeper's Tomb.
Verant promptly shut the zone down, and buffed the warders to a point where you couldn't reasonably expect to kill all four. The third one, in fact, was only killable due to stacking buff issues. The fourth was neigh impossible. Well, until Itzlegend thought about it. He popped in IRC the day before, shot some shit with Furor, they talked about it, and came to the conclusion that it could be done. Conquest went into the tomb the very next day.
It took them a long time to set up, and even longer to execute, but eventually they were wearing the fourth warder down to a kill. Just as the raid figured everything was going smoothly, Conquest wiped on the fourth warder, and then the GMs deathtouched it and banned Conquest.