Tactics for the Swamp (Fortress).

There's plenty to discuss about Mages and Knights, let's save that for another topic.
But you've convinced me about defense. Let's talk about the tactics of playing as this faction. The speed of the units doesn't allow you to immediately rush the enemy, and waiting for the enemy without strong archers means incurring losses. Regarding archers, the Swamp faction definitely loses to everyone.
Only the Serpent Flies move normally, but one in the field is not a warrior. You know how quickly they die.
Other factions have units of levels 6 and 7 that can reach the enemy in one turn (Necropolis, Haven, Inferno, etc.). As a result, they deal significant damage, supported again by archers.