Unfamiliar of his past, Thomassy was certain of only one thing - that he was definitely glad to be out of Dalaran once his training was complete. Leaving behind mentors and friends such as Nicholas Drake, an old drinking partner, Thomassy set off to find his place in the world. After several daring adventures, including teaming up with agents of Ravenholdt at unexpected times, Thomassy realised that Dalaran's patience was wearing thin. Thomassy was at risk of becoming a rogue mage, and Dalaran would never stand for such a thing.
Settling for a compromise, Thomassy eventually wound up as court wizard for King Alford Menethil of Lordaeron, having befriended him in their younger years when Alford had been on several state visits to Dalaran as crown prince. As Alford's court wizard, Thomassy finally found his place in the world. Free of wizard bureaucracy, he found Lordaeron paperwork to be a lot less tiring or complicated.
The arrival of the Great War of Lordaeron signalled an opportunity that Thomassy had been waiting for. It was a chance to shine, metaphorically speaking - as Thomassy fully intended to light up the skies with blazing fire and deadly magic. Dalaran had suffered a civil war, like many nations across the continent. Thomassy and Alford sympathized with the rebel Kirin Mora, and Thomassy aided in the defence of Ambermill with his illusions. He helped secure an alliance between his old compatriot, Grigori Dosantos, and Lordaeron. Thomassy used the Kirin Mora to help him activate the Black Iron Golems that had been discovered in the gardens of Lordaeron.
When Andol Corin led a force that took command of Lordaeron City, Thomassy was dismayed to realise that his nemesis, the Bruxist wizard Oran, was likely freed in the takeover. Nonetheless, Thomassy continued to do his job and managed to get Alford out of the city alive.
Eventually, Thomassy was forced to sacrifice his eyesight in battle with Augusta in order to defeat her. He then joined in the Battle of Dalaran, where he witnessed the death of his dear Alford. Afterwards, he was eventually recruited by his old friend, Nikolai Tymoshenko, to use blood magic to fight the Crimson March.