Tactics for the Swamp (Fortress).

To avoid being overly verbose, I'll briefly reiterate: the "weakness" or "strength" of Fortress or Inferno largely depends on the resources available in the lands surrounding your home city, and on when your neighbors "visit." Fortress with troops of levels 1-3, and Inferno with troops of levels 1-4, are relatively weak. Fortress excels due to the special abilities of its troops of levels 4-7, and Inferno due to its troops of levels 6-7. But first, you need to acquire enough of them.
In most cases, a player controlling Fortress should capture a city of another race to gain additional troops and learn useful spells.