Units have traits which reflect aspects of their character. Traits are assigned randomly to units when they are created. Most units receive two traits.
The possible traits for most units are as follows:
Intelligent units require 20% less experience than usual to advance (Trolls do not get this trait). Intelligent units are very useful at the beginning of a campaign as they can advance to higher levels more quickly. Later in campaigns Intelligent is not quite as useful because the After Maximum Level Advancement (AMLA) is not as significant a change as advancing a level. If you have many maximum level units you may wish to recall units with more useful traits.
Quick units have 1 extra movement point, but 5% less HP than usual. Quick is the most noticeable trait, particularly in slower moving units such as trolls or heavy infantry. Units with the Quick trait often have greatly increased mobility in rough terrain, which can be important to consider when deploying your forces. Also, Quick units aren’t quite as tough as units without this trait and are subsequently less good at holding contested positions.
Resilient units have 4 HP plus 1 HP per level more than usual. Resilient units can be useful at all stages of a campaign, and this is a useful trait for all units. Resilient is often most helpful as a trait when it occurs in a unit that has some combination of low hitpoints, good defense, or high resistances. Resilient units are especially useful for holding strategic positions against opponents.
Strong units do 1 more damage for every successful strike in melee combat, and have 1 more HP. While useful for any close-combat unit, Strong is most effective for units who have a high number of swings such as the Elvish Fighter. Strong units can be very useful when a tiny bit of extra damage is all that is needed to turn a damaging stroke into a killing blow.
There are also some traits that are assigned only for certain units or only for units of a certain race. These are:
Dextrous units do 1 more damage for every successful strike in ranged combat. Dextrous is a trait possessed only by Elves. The Elven people are known for their uncanny grace, and their great facility with the bow. Some, however, are gifted with natural talent that exceeds their brethren. These elves inflict an additional point of damage with each arrow.
Renowned for their vitality, some dwarves are sturdier than others and can rest heal even when traveling or fighting. Healthy units have 1 HP plus 1 HP per level more than usual and rest heal the usual 2 HP after each turn regardless.
Does not suffer from a negative attack bonus during its unfavorable time of day (Heavy Infantry, Necrophage, Trolls, Walking Corpses).
There are also some traits that are not assigned randomly. These traits can either be assigned by the scenario designer or are always assigned based on the unit type:
Loyal units don’t incur upkeep. Most units incur an upkeep cost at the end of every turn, which is equal to their level. Loyal units do not incur this cost. During campaigns, certain units may opt to join the player’s forces of their own volition. These units are marked with the Loyal trait. Although they may require payment to be recalled, they never incur any upkeep costs. This can make them invaluable during a long campaign, when gold is in short supply. This trait is never given to recruited units, so it may be unwise to dismiss such units or to send them to a foolish death.
Undead units are immune to poison, also drain and plague doesn’t work on them. Undead units generally have Undead as their only trait. Since Undead units are the bodies of the dead, risen to fight again, poison has no effect upon them. This can make them invaluable in dealing with foes who use poison in conjunction with their attacks.
Mechanical units aren’t alive and thus are immune to poison, also drain and plague doesn’t work on them. Mechanical units generally have Mechanical as their only trait.