For seven years he trained in ancient magical arts, until he mastered his craft. It is said that he blazed with the brilliance of Magnus himself, and was surrounded by a brilliant glowing light. Some say he was the son of Magnus, but those legends are most likely hyperbole. He returned from Artaeum and became the court wizard of Wulfharth, and proved himself a experienced politician as well as a mighty wizard. As a reward for his service, Wulfharth declared him Jarl of Winterhold, the least prosperous Hold in Skyrim, with only a small village in it. Shalidor grew displeased at the tiny city and constructed a great palace (that was to become the College of Winterhold) and renovated the village into a city as large as Winterhold itself. From across the world, students came to learn from him. It is said that his reputation even extended outside Mundus, as the Daedra he summoned gave him respect more than any Daedra would give a mortal.
He grew tired of politics and moved to the ruins of Bromjunaar. He constructed great mazes to test his heirs. Around this time he is believed to have discovered Glamoril (The Secret of Life), and hid it in the deepest part of the ruins. It is said that he stole Glamoril from Akatosh himself. Theories about Glamoril abound, from the secret of immortality to a way to create new life to the very meaning of life itself. Whatever it was, Shalidor claimed that only someone even greater than himself could find it, and judging by the deaths of seasoned adventurers, he was right. It is said that he created many artifacts during this time, including the Shroud of Shalidor (Which is now worn by the Archmage of Winterhold), the Spell Breaker (A shield he enchanted as a gift to a Dwarven friend) and Chillrend (A sword said to have been made from Atmoran ice).
The Dwemer of Skyrim marched to the east in order to assist their cousins during the Battle of Red Mountain. Shalidor was hundreds of years old by this point, and more apathetic than ever. The High King begged him to help, and Shalidor only agreed once he saw his old master Wulfharth leading the Nords. Shalidor intercepted the Dwarf armies and single handedly held them off. Dozens of Daedra were summoned, and every Dwemer that fell in battle was raised to fight for Shalidor beyond the grave. Shalidor's undoing, ironically, was the shield he helped to make. The Dwarven king used Spellbreaker to reflect a bolt of lighting into Shalidor's eyes, blinding him. Just before a sword was about to cut off Shalidor's head, the Dwemer disappeared, Shalidor getting a large scar on the back of his neck. Permanently blinded, Shalidor had to be brought back to his lair by servants. Shalidor was angered by how he failed there. The battle was his only loss, and his hunger for power grew immensely, so that he may never fail again. He created a portal to Aetherius, realm of pure magic, that he may gain power from it and ascend to godhood. He was never seen again. Some say that he has become a minor planet, like Ban Daar or Mannimarco. Others say that he simply died there, annihilated by the light of Aetherius. Nobody knows for certain what happened that fateful night.