Excellent swamp castle. I usually divide my army into 2 groups: fast and slow units, and combine them before attacking castles. The first army consists of Wyverns and Serpent Riders. Sometimes I add Hydras to them. And the second army consists of all the other, slower but stronger units. By the way, I advise you to pay attention to water magic when leveling up. It is very important for swamp creatures. The most valuable spells here are: Teleport (absolutely necessary for attacking, for example, to block enemy archers with Basilisks), Clone, and Prayer.