This is something that has been up for debate. However I believe that there is nothing magical about the number 13, and the reason 13 Aes Sedai can shield any single male is simply because any 13 AS when combined are always stronger.

However what Asmodean says when he talks about this implies that this is only because AS have a strength-limit to joining, and 13 Sorileas/Morgases could not shield Rand. Rand himself during the meeting with Tuon seems to think that by drawing "a little extra" from the Choedan Kal he would be able to resist a full circle, again implying that it is simply a matter of strength. And I would think since Rand was almost LTT at that point, he would have known if there was some mysterious property to circles of 13.

So essentially, if Rand had somehow increased in raw OP power significantly, he could indeed be able to overpower a shield made by even 13 sisters.



Thats the question. I think OP increase would make it possible for Rand to break a shield of 13, but until someone explains this, it could just be ta'veren or light!aura or whatever that would allow him to break free.