Who is "The Master"?!
"The Master" is the well-known name for the creator of the X Universe, Ephrael. Ephrael is classified as whole different type of God known as the Creator. The Creator group includes: Ephrael, L'asharc, Stigma, and Dogma.
Ephrael: As "The Master"
As a Creator, Ephrael barely leaves Ascension. Unlike any of the other gods, when Ephrael leaves Ascension, he can hear the thoughts of all of his creations (every creature in the X Universe), a clear reason as to why he never leaves. Ephrael basically oversees the running and order of the X Universe, while all of its inhabitants believe that he is some resigned deity that will not answer their prayers. Ephrael has basically resigned his deity status while he rests from the creation of the X Universe.
Ephrael: As an Enforcer
Ephrael is known as the Elemental Archfiend because he can break down the elements into pure Life Essence and use it against his opponents. It is also known that no one attempts to attack him because he can simply "erase" any inhabitant of the X Universe that wishes to oppose him. Ephrael is known to the other Gods as a sort of leader; he gives them orders, assembles meetings, and even make sure that their respective powers are kept in balance. He is also in charge of The Great Divide, even after its destruction; making sure no inhabitants from Dread enter the X Universe.
Ephrael has the desirable power to assume control of the entire Lifethread of the X Universe and use it to bolster his power. On top of that, while he does this, everyone else's power and life dwindles continuously until he relinqueshes control. Ephrael can disassemble any element thrown at him, has masterful control over psychic energy, and can deconstruct one of his creations' makeups to return them to the Lifethread (known as "erasing").
Ephrael: A History
Ephrael was not the original creator of X, he is not even a full being. Ephrael is a fragment of the deity Dogma, and can only achieve a full being form by combining with his brother, L'asharc, a fragment of the deity Stigma. Ephrael's full combined form is named and known as Arenartos. Ephrael has only been known to leave Ascension twice, once at the start of The Balance War, and the last at the end of it. Ephrael is continuously trying to make himself his own entity by trying to arrange the deaths of Stigma and Dogma.