The Being behind the name Master Gill is a Human born as Alverian Yrsiin. The man became one of the most influential persona across the Universe, especially in the works along The Deathwatch. In his current state, Master Gill serves as the head figure of the Death Cathedral of Mandrealis. He is in possession of a very powerful and intricate tome; The Necromantic Tome of Death.
Born in a small family of Magi, Alverian was the child of three not to possess initial arcane skills. He learned to deal with this disadvantage that he had compared to his siblings and still became a powerful Magician, though were his parents never in favor of him. They despised his lack of born potential and were stricter in his training to compensate his missing powers.
When Alverian turned sixteen, his whole family was enrolled to fight in a war between rivaling families. Though armed with the arcane potential like no other, Alverian lacked the experience of fighting and battling others. Unable to compete against the warriors and mages of the enemy, the young man turned away from the fighting and fled the battlefield.
The emotions of the battle and the rather grim past pushed Alverian to his limits, making him flee the country, until he met a traveling merchant of exotic wares. The man offered safe travels for the boy, if he would in return kill a person for him at their destination. Alverian listened to the man's request and agreed to make the scoundrel pay in blood. The two traveled to Alverian's old home and met his father.
In a fierce battle between two strong mages, Alverian's father underestimated his own son and fell to the devastating powers that he taught him all the years before. With that, Alverian felt at peace with his past and decided to travel with the merchant.
In order to make peace with his past, Alverian removed his family name and took the name "Yrsiin", which means Outcast in the mage dialect of the Language of Old. For many years, the man traveled far and wide, even into the dark alleys of The Market. He learned a lot about Magic, Faith and the power of the Soul, at which point he became a powerful Being.
His abilities did not go unnoticed, for he met many people that asked for his allegiance. He turned down any offer of honor, glory and pride, until he met another familiar face that he wished to be gone forever; his older sister, now a powerful mage of the Arcana Academia. She offered redemption for his parricide, but the past was still a thorn in the memory of the young man.
The two battled in the streets of the Market, until his sister was slain by a third party. The young woman that joined the fighting collected the Soul of Alverian's sister. She saw the potential in the man's skills and offered him to join The Deathwatch. Seeing the powers of Necromancy, an arcane teaching that he had yet to learn, he signed the contract.
For four thousand years, Alverian worked under the name Yrsiin as Deathguard of the Third Cadre. He hunted Souls in great numbers, killed many Beings that were unwanted and executed Souls that the Gods want to get rid of.
The aspiring Champion of the Exiled One learned the arts of Necromancy and gained the trust of the Deathwatch members and their God. His skills grew too quickly after a while, deeming him a potential God that the others did not want. His powers were partially sealed inside a tome that he is now forced to guard, his contract revised and suspended.
From that day on, Alverian Yrsiin fell into oblivion, leaving the sight of the Gods. His knowledge made him a valuable source for Death Cultists, though should no one know of his true nature. Once more, Alverian cast off his name and became Master Gill of the Death Cathedral of Mandrealis, living there for the past century as the headmaster and teacher.