I gave up Necropolis and a castle with a built-up stronghold. The first couple of weeks were tough, but I found a decent artifact and a couple of good items for Necropolis. In the middle of week 4, I took the main opponent's castle with 2.5k skeletons and 80 gold per week. I chased him for a week. I had to defend the approaches to his main castle because I was afraid of gold giants. In the end, I took almost all the castles and, with Rings of the Magi, Crown of the Magi, and Elixir, and 3.8k skeletons, I killed the main opponent, despite him having assembled an alliance of angels.
Thanks for the game!