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IIrc, the 10 Great Warriors are all irregulars, since they entered the Tower with Zahard. People like Grace Mirchea Luslec, who helped the 10 Great Warriors while they were climbing the Tower, aren't irregulars.
Like syx mentionned on the post under yours, some people that were living in the tower like Grace Mirchea Luslec helped Zahards and the 10 warriors to climb the tower. The one who helped them are not irregulars.
That's all we know for now.
Here's a better explanation taken from Wiki (everything in that wiki comes from the author's afterwords).
Last edited by Nast.J; August 04, 2013 at 12:27 PM.