Author: Estyrien al'Halien
Like most Aes Sedai, Carenna had a trick involving the One Power that she did not tell anybody about. She could use saidar to eavesdrop. When Nynaeve told the rebels how to create the weave, Carenna picked up on it very quickly and even claimed that she could use the weave to talk to someone at a distance.
(Reference: Lord of Chaos, Prologue)