I started without any Castles. At first, I focused on building up my economy, but before I could build a Town Hall, I had to build a Castle to have some skeleton production. By the second week, I captured a second Castle and only built up the economy there. In the third week, I built dragons.
The first encounter with Raul happened in the center of the map. I saw Gunnar and attacked. I had more troops, and our skills were almost the same, so he surrendered. Then, I bought a whole army and moved towards Raul, attacking his main Castle. I had more troops, but he had better magic. In the end, when he had only 1 black dragon and 1 vampire lord left, and I still had about 100 zombies and 200 skeletons, I couldn't do anything because the dragons were just flying around, and I was out of mana. I had to surrender. But after buying a whole army again, I attacked him a second time. He hid in his second Castle, but I didn't dare attack the Castle, so I went for his main Castle and took it almost without a fight on the 7th day. I stayed in the Castle, and since the opponent had nothing else to do, he attacked me and lost. There was no point in continuing the game, and the opponent surrendered