Third Degree Reiki adds the symbol Dai Ko Myo or dai ku myo (dye koo myo, (mm yoh long o)Self empowerment, Intuition, Creativity , and Spiritual connection it enables recognition and clarity about your true path. Less is known about this most powerful of the Reiki energy functions because until quite recently there have been very few people empowered to use it so it is still somewhat unexplored . It activates a powerful energy for Self Empowerment it is used for opening Spiritual connection and intuition and cellular healing .once you are attuned for this energy I recommend using it for treating yourself and others each time you activate Reiki . It is said to work at the cellular and genetic levels and is valuable for treating Migraine Headaches. Many people have found that the Reiki Attunement particularly to this Reiki tool increases the intuitive and psychic awareness that they can comfortably access.

I have heard this called the vocational or life purpose mode because it often seems to initiate dramatic changes in career and lifestyle. It is also used as a Manifestation energy by some as is Cho Ku Rei the power boost from second degree Reiki . to use for manifestation you activate this energy and clearly visualize what you intend to manifest this will not bring you things that are not in accord with your high self and soul purpose.

The Dai ku Myo is also known as the Master Symbol. This is the energy that the Reiki master activates to do the Attunements that make the Reiki energies permanently accessible to the new practitioner. Many Reiki Masters do a non master three a attunement that activates the Dai ku myo as the spiritual intuitive energy but does not give the ability to do attunements.

The Dai Ku Myo is in Buddhist teaching the representation of unlimited potential and of all spiritual teachings and natural laws of the universe All of the functions which have been added to variations of Reiki   are actually contained in the Dai Ku Myo.

I personally think that these symbols were not ever considered secret   by Dr Usui but were in fact matter of fact activation's of intent by someone well versed in Buddhist esoteric meanings this is my personal opinion based on a 30 year Buddhist practice. Cho-Ku-rei (organizing the essence of the spiritual life force) hon sha ze sho nen (living correctly  without barriers, universal right action) Dai ku myo ( the great essence of all sacred laws) I was not familiar with Sei He Ki before.

Some Reiki Teachers Use DKM only during attunements, others work with it for all treatments.