A tetrarch is a Greek term that strictly identifies one of four governors of a divided province. The Romans used the term for one level of military commander. The term is thus used for any subordinate or dependent prince, or for a petty sovereign. Herod the tetrarch had the title of king (Matt. 14:9).
Herod and Phasael, the sons of Antipater, were the first tetrarchs in Palestine.
See also the Tetrarchy established by Diocletian in 293 CE, under which the Roman Empire was divided among two Augusti and two Caesars.
It appears that none of the Tetrarchs can generate this field independently of the others, it is likely that this field could only be generated as a group effort.
Like all the Tetrarchs, Yod claims to be a force of the universe, but is merely an extremely powerful individual with an overblown ego.
The other Tetrarchs will even ask Yod what their next move is to be and his word seems to be final.
Tetrarch is a Greek term for a holder of Imperial office under a Tetrarchy (form of government with four con-collegial heads; especially the Roman Empire since Emperor Diocletian's 293AD reform).
A Macedonian officer in charge of a unit associated with the number four (tetra), such as a quarter of a larger unit (such as a phalanx, or in one case a 'company' of 64 footmen), or comprising four smaller units (in one case 4 lochoi, each under a lochagos).
Herod Antipas (Ruler of Judea and tetrarch in Galilee)