Starting from turn 126, he began taking Dragon Utopias – scouted out 3 of them, which gave him a good artifact.
He went to take a Dragon Utopia right under Maretti's nose; along the way, he took Castle computers away from him. This earned him another artifact and a hat that was useful throughout level 5.
After that, he systematically cleared the map, while Maretti holed up in a corner in the super treasure hunt.
On turn 146, after having taken all the castles, he attacked with siege weapons. The stats were even, but I had 75 griffins with morale and luck bonuses, plus +2 speed, while he had an elite unit and a sniper archer. In the first round, I destroyed 25 out of his 50 griffins, and after that, he had nothing left to kill my griffins with.
Thanks for the game!