Tower tactics.

The Tower is the weakest castle. n2k is right; check it in the map editor against other castles. The Tower's only hope is to hide its archers behind the terrain and units and shoot everyone while remaining safe, but as soon as a hero-warrior with tactics appears, this castle collapses like a soap bubble. Simply placing troops in the center of the map and using speed spells equals the Tower's demise. The Swamp also easily tears through the Tower in this way. Flies defeat archers, wyverns defeat giants, nagas, or titans, hydras attack either titans and nagas or mages and giants, basilisks attack titans hoping to turn them to stone, and if the hero has a gorgon proficiency, then gorgons kill titans, and usually gnolls don't make it on the first turn. It all starts with melee combat, and the Tower dies on the 2nd or 3rd turn. The Tower itself should use tactics. By the way, golems performed well against gorgons.