In the first week, I captured 4 Djinn dens and 4 resource sites. One castle on the respawn point and a couple of hives – all very far apart. Since there were Djinn dens, I placed a castle with Nagas in the citadel instead.
On turn 122, a level 1 hero breaks through to the enemy's main town – 35 Hydras and I clear the center, where I take three Giant Spider dens, 2 Naga dens, 1 Djinn den, and the Air magic book.
I cleared everything for two weeks, but nothing happened. I played it safe :)
I went to his town and easily defeated him.
Thanks for the game.