The Great Lord of the Dark provides his most favored minions with the True Power that comes directly from him. It is even more addictive and dangerous than the One Power. (ACoS,Ch20) Traveling using the True Power involves ripping a hole in the Pattern. (ACoS,Ch20) Users of the True Power such as Moridin develop saa or black spots that travel across the eyes. (ACoS,Ch25) In the Age of Legends only thirty were given this privilege by the Great Lord. (ACoS,Ch25)
The gholam can detect True Power weaves. He feels it as an itch somewhat different from the One Power. (TPoD,Ch2)
Since he became Nae'blis, only Moridin is allowed access to the True Power. (WH,Ch13)
Rand believes the stranger is in his head because his One Power balefire touched Moridin's True Power balefire. (KoD,Ch18)
The Great Lord makes the True Power available to Rand and he accepts it. He uses it to destroy the Domination Band and then to balefire Semirhage and Elza. (TGS,Ch22)
The Great Lord grants Graendal limited access to the True Power as a reward for her successes. (ToM,Prologue)
Rand says that the Far Madding guardian only blocks the One Power implying that it does not block the True Power.(ToM,Ch51)