| Perhaps this old man can be of some use.
Clues to Crowley's age and power come from his statement of the amount of runes embedded in his body. It is said he has 100 runes attached to his body. He is also referenced in texts as "great and ancient" as well as the discoverer of rune unites.
The goal of his life is said to be to find a way to equal or surpass the power of the 27 True Runes through skilled application of ordinary rune magic and he spends his days in research and training towards this goal.
Anyway, now Crowley's eyes are irreparably damaged.
At some point, he took Mazus as his disciple. It is said that the two once had a fierce battle during which they unleashed so much magical power that they leveled three mountains and made it rain for a whole week. Piccolo claims to have been the third disciple of Crowley's.
Crowley was discovered training and researching in the Cave of the Past at Qlon Temple, where he expressed surprise at being discovered. He agreed to be recruited by the Toran Liberation Army, stating that he'd like to enjoy the sunshine. It is said that while he aided the Liberation Army, he only used a small fraction of his power doing so despite the prowess he displayed being the most powerful seen on the battlefield.
Following the end of the Gate Rune War, Crowley returned to the caverns, harboring a distaste for world affairs. Mazus, who would participate three years later in the Dunan Unification War, set out to duel his former master once again, but it's unknown if they actually met.