Guardian
At first Esdras aimed to become an alchemist. His plan was almost perfect. But life is not that convenient.
Alchemists were respected, and admired within the mage community, because of their ability to create mana potions. Most importantly, they had an irreplaceable value.
Low supply and high demand.
It would make sense for him to aim for this position, not only because of the previous reasons, but also because it was a gold minting machine.
It would be a perfect place for him to sell the potions he acquired from the dungeon while reducing this suspicion that would be pointed at him.
Of course, people would be suspicious that he alone managed to create not one but two new potions. The Octarine tower would probably launch an investigation into him.
But it will probably be only for show. Being the only one who knew the formula to the two new potions would make the executives hesitant to displeased him.