you can win against the Castle; it's not that scary, but it's strong and dangerous for the Swamp faction: 1. Choose between these heroes: Tazar (it's better to choose him if you can definitely level him up to 20 and higher, then the defense percentage will increase significantly), Bron (good at the start, as he immediately provides Basilisks), I also like the hero Korbach (specializes in Serpents, which can be very useful, as you often have to throw Serpents at the enemy unit right away, and he also seems to have the "Pathfinding" skill). 2. Fast development: you can really build a Fortress faster than a Castle. 3. Battle tactics: Gnolls are cannon fodder, a distracting unit that takes the enemy's retaliation, Lizards are quite strong archers, Serpents are the most useful unit; weaken the enemy's strongest units with them, and you can also use them to deflect attacks, block archers, Basilisks are shock tanks, the main strong combat unit (if you're lucky, they can turn the enemy into stone for 3 turns, taking them out of the game) – just a shock unit for fighting all enemies in general [maybe this is because I start the game with Bron], Gorgons: throw them at the strongest enemies or those you fear the most, Hydras: try to make as many enemies as possible be hit by their attack (they attack all cells around them), attack with Wyverns whoever is more convenient and hurts more. 4. Magic: if the game takes place on large maps where heroes can be well-leveled up, it makes sense to develop Wisdom and Expert Water (mass healing, blessing, weakness, forgetfulness, removing all spells, teleport, clone). It's still good to be able to support your troops with spells. Specifically against the Castle: well, basically the same as against the others, everything according to the usual and convenient scheme. It makes sense to use Gorgons, Wyverns, Basilisks, and someone else to attack one unit at a time and eliminate them from the game. You can use Serpents to block archers, send Gorgons against Angels or Champions (depending on who is more dangerous), Wyverns and Basilisks are the main attack force, Gnolls are cannon fodder and a distraction, archers (it's better to attack those who are closer and more convenient, so that there is no penalty or to help Wyverns and Basilisks), Hydras – against several enemies. With equal forces and heroes, I think the Swamp will still win. When playing as the Fortress, I'm afraid to go against: Towers, Dungeons, Citadels, and Necropolis.