The Sixty-Six Secret Arts are a collection of powerful and extraordinary techniques available only to those of the Illuminati who have gone under the society's intensive hand-to-hand combat training program, where the ability to wield ki and elemental power is developed through such tutelage, and by genetic alterations to enhance the properties of the participants.
Training to master these techniques is said to come from mastery over specific elements by merging them into one's aura. Mastering them all is said to be impossible, as they make the use of all known elemental affinities, while the known maximum elemental capacity in a human is three.
Two of these techniques revealed throughout the series are the Aegis Reflector learned by Urien, and Resurrection, learned by Gill.