I don't know why everyone is saying that the balefire option would destroy the Pattern - I don't think Rand would be attempting to remove its effects from all of history, just the taint, so he would the minimum amount of balefire necessary to destroy it, thus keeping the timeline changes to a minimum.
He is not trying to remove the Taint's past effect on history, but its present effect on Saidin.
Taint Cleansing
in Wheel of Time Books
Posted
I don't know why everyone is saying that the balefire option would destroy the Pattern - I don't think Rand would be attempting to remove its effects from all of history, just the taint, so he would the minimum amount of balefire necessary to destroy it, thus keeping the timeline changes to a minimum.
He is not trying to remove the Taint's past effect on history, but its present effect on Saidin.