Absolute Virtue is an Aern High Notorious Monster in Final Fantasy XI, and is the hardest enemy in the game, and bar-none the hardest boss in all of the Final Fantasy series, as it has never once been legitimately beaten in its current form by anyone in the world. In 2008, the development team released an "educational" video with hints on how to defeat Absolute Virtue. This primarily involved the use of 2-Hour abilities in tandem with Absolute Virtue's use, somehow locking them. The video (along with the vast, sweeping majority of content put out by the developers) is horrendously vague, involving simply showing different parts of what seem like multiple attempts at the monsters by developer characters immune to its attacks, often zooming in at the dialogue box as if to show players something important. This has often been made fun of by the endgame community for its ridiculousness and complete lack of aid to the players (e.g. "Clearly we are not zooming in on the text hard enough, otherwise we would have beaten it by now.")
After the weakening patch that was moreover a response to the news reports filed against the marathon kill attempts of comparable foe Pandemonium Warden , Absolute Virtue now only has some 70,000 HP, far less than other Notorious Monsters in the game, and significantly less than the strongest enemies in other Final Fantasy titles (Yiazmat comes immediately to mind). What makes Absolute Virtue so "impossible," though, is its unique way to stack multiple 2-Hour abilities (essentially Final Fantasy XI's Job System's strongest, most devastating techniques available to players...
One such ability, Benediction, the White Mage 2-Hour, is especially frustrating, as it will heal Absolute Virtue's HP to full instantaneously at any point in the conflict, as well as remove its negative status effects. It can do this multiple times.
Consequently, during brief spans of time, Absolute Virtue became susceptible to various means of killing via crude exploitation of terrain and the popular "Dark Knight Zerg" strategy (right after the weakening patch) used on many other monsters in the game. The first wave of kills by illegitimate means took place via use of a terrain exploit, coined the "Wall of Justice", wherein players positioned themselves behind a wall that had unique programming enabling them to attack Absolute Virtue but preventing the opposite. For completely unexplained reasons, game masters decided that users of this exploit were to be permanently banned from play, and the wall was quickly re-coded without mention in update notes. Regardless, because of these brief windows of opportunity, some of Absolute Virtue's dropped treasure items do exist in-game and make their rounds in the Real-Money-Trade community, often selling for tens of millions of Gil, or on illegal auction websites sometimes for more than $1,000.
Today, the playerbase has essentially given up entirely on trying to beat the monster...