Lanfear, Matrim Cauthon, One Power, Black Ajah, angreal, ter'angreal
Robert Jordan has spoken...
In The Dragon Reborn, Lanfear visits Mat as he is recuperating from his One Power surgery over the dagger. At one point she stretches out her hand towards him and he feels a tingle going over him, somebody interrupts them, and she turns her head and sobs, at about the same time a member of Black Ajah stole angreal and ter'angreal out of the Tower cache, one of which was a ter'angreal that was known to have some effect on chance. So it was about this time that Mat's really really really weird luck and the dice rolling in his head began. Is this a connection or coincidence?
That is a coincidence. When they say that Mat has the Dark One's own luck, he can get as mad as he wants to, but in a way it is true. It wasn't a gift from Lanfear, though.