The fortress suffers from a lack of strong low- and high-level troops. The gnoll is a fairly good first-level troop, but the lizardman, despite its ranged attack, is one of the weaker second-level creatures. Serpent flies, and even the upgraded dragon flies, are only useful because of their speed as they may allow you to cast spells first, but otherwise, they are too weak to do much more than annoy your opponents. Only in great numbers are they useful. Basilisks are surprisingly strong compared to other fourth-level troops, and they remain one of the best fourth-level units. Gorgons appear strong, but when matched against such creatures as minotaurs and rocs, the gorgons will generally lose. Gorgons offer good defense and can soak up a lot of punishment. The wyvern is pretty weak for a sixth-level creature, but has good speed and flight. Luckily, you can acquire it within three days, so build the wyvern's nest quickly for an immediate advantage. The hydra is itself a strong unit, but lacking superior speed and any outstanding special abilities, is probably the weakest of the seventh-level creatures. But it becomes useful if you want to attack multiple enemies at once. Definitely upgrade your troops if you have a fortress town; the troops here need the extra durability and speed that upgrading brings.
The saving grace for the fortress creatures are their special abilities. The basilisk petrification ability and the gorgon's death stare are useful when they occur. Petrification allows you to direct your attention to other creatures, and the gorgon's death state has a 10 percent chance to kill one enemy unit outright for every 10 mighty gorgons. The poison of the wyvern monarchs, though, isn't nearly as useful, as it merely reduces the first creature's hit points in the poisoned stack by 50 percent.
Fortress creatures require more magical aid to be effective. Use teleport spells to instantly move gorgons, basilisks, and hydras across the map to strike immediately. If you can do this, and support them with magical aides like bless, bloodlust, and stone skin, then your troops will be much more effective.
Two flying units (one mid and one late)
Mid level creatures are strong
Can get wyverns very early
Heroes' defense bonus makes monsters tough
Most creature dwellings are cheap
Good special buildings
Very weak in magic
Only one weak ranged attacker
Weak late game units
Thanks to The Nether Gods team for the contents of this page!