Tarmon Gai'don, (pronounced: TAHR-mohn GAY-dohn) also called the Last Battle and The Time of Return by Darkfriends, is the apocalyptic confrontation between the Dragon Reborn, Rand al'Thor, and the Dark One that is prophesied will end the Third Age of the Wheel of Time. According to prophecy, if the Dark One prevails he will escape from his prison and remake all of time and space in his image. If the Dragon Reborn prevails, the Dark One's effect will be negated and it is presumed that his prison will be re-sealed. However, the prophecies are unclear about the specifics of this eventuality, and it has proven a subject of some debate between philosophers.
According to the Prophecies of the Dragon there are certain signs that will proclaim the imminence of the Last Battle. The rebirth of the Dragon is the earliest such sign, and others include the breaking of the Aiel and their return to the Westlands and the splitting of the Aes Sedai. It is also prophesied that the Seanchan and the Dragon Reborn will come to an accord, but the Prophecies are unclear in this regard: some have the Dragon Reborn kneeling in subjugation to the Crystal Throne, others say that he will bind the Nine Moons (the sigil of the Seanchan Imperial Court) to him; it is possible these conditions are not exclusive of one another. It is also possible that Ishamael may have tampered with the Seanchan version of the prophecies, or that Seanchans turned them into propaganda themselves.
However, the Prophecies specifically state that the clearest sign of the Last Battle will be the return of the dead to plague the living. Early in 1000 NE inhabitants of the Westlands, possibly the whole world, began to see images of people long dead, sometimes just individuals but sometimes entire long-destroyed cities or towns that appear and then vanish. This is the clearest indication that the Last Battle will come in weeks or months, not years or decades. Around this time 'ripples' in the fabric of reality were detected, suggesting that the entire Pattern could unravel if the Dark One broke free of his prison altogether.
The nature of the Last Battle has been debated. Some have suggested a new version of the Trolloc Wars, with hordes of Shadowspawn pouring out of the Great Blight to overrun the world, along with the emergence in force of Darkfriends and Dreadlords to lead them. It is believed that wolves will fight alongside men and the dead heroes will return when the Horn of Valere is blown. Something that most of the prophecies and legends agree on is that the Dragon Reborn's blood must be on the slopes of Shayol Ghul and that the Dragon Reborn will break the world a second time, even if he is victorious.
Philosophers such as Herid Fel have debated an essential conundrum of the Last Battle, namely that the Dragon Reborn cannot simply re-patch the Bore because the Dark One's prison must be whole once more when the Wheel of Time turns and the Age of Legends comes again, when the Aes Sedai of that Age create the Bore in the first place. Herid Fel was investigating how this conundrum may be solved and had apparently come to an important conclusion involving 'clearing the rubble'; however, he was killed by the gholam before he could alert Rand al'Thor, suggesting the Shadow considered his conclusion to be highly dangerous. Both Min and Rand have taken his cryptic note to mean that the remaining seals must be destroyed before the re-sealing can proceed.
Brandon Sanderson has confirmed that the Last Battle will feature prominently in the final triad of books. Tarmon Gai'don will likely be the main focus of the third volume, and was for a time the working title of Book 14.
Tarmon Gai'don is phonetically similar to the word and concept of Armageddon.