In 1.4 patch this faction was renamed to "Monsters".
The Nature faction consists of all the wild beasts that are native to Ardania and its alternate planes. They are hostile to all Great Mages as well as to the Neutral faction. They have the ability to take over any city if they attack them and get the city low enough, just like any player can. They can be identified by a brown color code.

These monsters, aside from the ones that appear in the world at the start of the game, periodically spawn from nests that are specific to one, or multiple types of beast. These nests can be looted by moving a unit into their hex. Depending on the type of nest, this may give you a generous amount of gold, mana, or both. There is also a small chance that it grants you a unit from the nest for you to control, or an Arcane spell that has not yet been researched.

Many types of nests and the monsters they spawn can only be found on other planes, such as Dragon Nests and Elemental Portals.

The types of monster nests and their rewards are listed below.

Name Spawns Loot Location Note
Garbage Dump Cockroaches, Ancient Cockroaches Gold Ardania
Ratmen Hole Rats, Strong Rats, Wild Ratmen Gold (40-60) Ardania Chance to recruit Trolls, Seasoned Goblin Spearmen, Goblin Sharpshooters
Imp Portal Imps, Demons Mana (100) Ardania, other planes
Bear Den Bears, Great Bears, Bearman Gold Ardania
Wolves Den Wolves, Old Wolves Gold (50) Ardania
Spider Nest Monster-Eating Spiders, Predator Spiders Gold (60) Ardania
Ogre Den Ogre Gold (50) Ardania
Free Rogues Guild Rogues, Hunters Gold (70) Ardania
Serpent Nest Wild Serpents Gold Ardania
Graveyard Skeleton Warriors, Skeleton Archers, Skeleton Veterans, Skeleton Snipers Gold (70) Ardania Chance to recruit Flying Galleus
Old Crypt Vampires, Green Bats Gold Ardania, other planes Chance to recruit Krolm's Housecarls, Paladins of Death, Ghosts, Ancient Liches, Dracolich
Hermit's House Noble Werewolves, Court Werewolves Gold Ardania, other planes Chance to recruit Shamans, Ratman Pirates
Dragon Nest Red Dragon Gold, Mana Other planes only Chance to recruit Shadow of Vendral
Elemental Portal Fire Elementals, Earth Elementals Gold, Mana Other planes only Chance to recruit Greater Earth Elemental, Greater Fire Elemental, Treewarden, Bearman
Magic Thicket Demonwood Gold, Mana Ardania, other planes
Whirpool of the Leviathan Leviathan Gold (110), Mana (125) Ardania, other planes Aquatic
Kraken Nest Kraken Gold Ardania, other planes Aquatic
Sea Serpent Reef Sea Serpent Gold Ardania, other planes Aquatic