Cleansing of saidin

From A Wheel of Time Wiki

The Cleansing of saidin was a cataclysmic event that occurred at the climax of Winter's Heart and was felt throughout the entire channeling world.

In Winter's Heart, Rand al'Thor made an extraordinary claim: he believed he had discovered how to cleanse the Dark One's 3000-year-old taint on saidin. While Rand was inside the redstone doorway ter'angreal, one of the questions he asked the Aelfinn was how to cleanse saidin. The answer to the question is never given, but it is known to be a riddle that Herid Fel said stated "sound principles, in both high philosophy and natural philosophy."

Rand and Nynaeve al'Meara used the two most powerful sa'angreal ever made, the Choedan Kal, one buried in Cairhien and the other on Tremalking to funnel the taint into Shadar Logoth. The evil in Shadar Logoth, which was born out of pure hate for the Shadow and the Dark One, caused the taint to "slide" off of saidin and into the city, where the two forces annihilated each other. These also caused a huge crater to form where Shador Logoth was. As of Books 10 and 11, it is believed that this process was entirely successful, although what it means for the Asha'man and other male channelers (not to mention the Red Ajah) remains to be seen.

While this was happening, there occurred the Battle near Shadar Logoth.