Lord Calphayus, also known as the “Prophet of the Dread Masters” was one of the Dread Master Councilors that was released by Imperial Heroes (player characters) during the Planetary Arc on Belsavis. During a raid to Asation by heroes, Calphayus would be responsible for releasing an ancient monstrosity known as the “Terror From Beyond” after the Dread Master’s pawn Kephess was defeated. He would then travel to Oricon with his cohort and attempt to control the galaxy with fear and the seeds of rage until the Council was defeated by an Operations Team of heroes.

Calphayus was most notably seen with a Cyan-Doublesaber, that he fought the Operations team of heroes with. His personal sanctum within the Dread Palace featured an elaborate garden that spawned crystal seeds. In this garden he was capable of enacting force-visions upon those that entered, forcing them visions of the distant past and futures of Oricon itself. After he was initially defeated by the heroes he fleed to the Council Chamber atop the Dread Palace where he and his fellow Dread Masters would then be struck down and killed.

However after the Dread Masters defeat within the Dread Palace, Calphayus claims to have not slipped into the void as his bretheren did, however he awoke after defeat and stumbled to the Republic base camp on Oricon, seeking redemption by the Jedi Order after his revival.
This final revalation is shown via a unique cutscene only for Republic Players at the end of the Oricon storyline.

Sources:

The Dread Masters – Codex Entry
The Dread Fortress – Codex Entry
Dread Palace Operation – Oricon – SWTOR
Oricon Republic Storyline – SWTOR
A Record of the Dread Masters – Lore Article on swtor.com