The game keeps track of exactly how much Create Undead damage (behaves like Poison Damage) and Melee Damage is delivered by a unit with Create Undead to each enemy unit on the battlefield. If an enemy unit is killed mostly or entirely by the Create Undead unit, or by Life Stealing Damage or Life Drain, it will return to the game as an Undead unit after the battle - and will now serve the opposing side.
There is exactly one unit type in the game that possesses Create Undead by default: the Ghouls. No other unit may acquire this ability from any source. However, compare this ability with Life Steal, another ability that can turn enemy units into Undead.
Ghouls are creatures pumped full of Death energy, to the point where their very touch can contaminate their foes with such energy. This magical "disease" has no discernible effect on the living, but its power will certainly be felt if the infected creature dies while carrying it. If so, the Death energy will erupt inside the creature, animating its rotting corpse. This corpse rises as an Undead creature - not living and not dead. Its mind, now blank and impressionable, can be influenced in order to change the creature's allegiance. The poor creature will now obey the orders of the master of the Ghouls that infected it, fighting relentlessly until, erm, death.
During combat, the game tracks the amount of damage done by any unit with Create Undead on any of its opponents. The damage count is unimportant - unless the damaged unit dies.
At the end of a battle, the game runs through each and every unit that has been destroyed during that battle. For each unit, it checks whether the following conditions are true:
- Is the unit either a Normal Unit or a Fantastic Unit?
- Did the majority of the damage caused to this unit come from an enemy unit possessing Create Undead?
- Did the unit's army either lose the battle or flee it?
- Does the opposing army contain fewer than 9 units?
If all four conditions are true, the unit is returned to the game with full Health and figures - but with two important changes: It is now an Undead unit, and now permanently belongs to the enemy!
- If this is a Normal Unit, it no longer has any Upkeep Cost.
- If this is a Fantastic Unit, its Upkeep Cost is increased by 50%.
- The unit gains several immunities to various forms of damage and effects, as common among Death creatures.
- The unit is permanently associated with the Death realm, and will be affected by spells/effects that only affect Death creatures.
- The unit no longer heals naturally each turn on the overland map. It cannot be healed by any healing spell.
- The unit ceases to gain any Experience. It does, however, retain any Experience level (and related bonuses) it had prior to the change.
(For a complete overview of these changes, read the article about Undead)
As a result, units with Create Undead can actually increase the size of their army as they advance, collecting new Undead units created out of enemy armies they encounter. Though these newly-created Undead units are easily lost (since they cannot be healed), they temporarily provide a boost of strength to the army, and can be used as "suicide troops" to slow down the enemy during the next battle.
Note: It is currently unknown how the game tracks the types of damage caused to a unit, in order to determine whether a Create Undead unit caused the majority of this damage. Also, it is unknown whether the conditions for creating an Undead unit require that Create Undead cause 50% or more of the unit's health at the start of the battle, or 50% or more of the unit's total Health. Test results are inconclusive and sometimes contradictory.
Units with Default Create Undead Edit
Exactly one unit in the game possesses Create Undead by default. It is a Fantastic Creature from the Death Realm:
Acquiring Life Steal Edit
There is no known way of adding Create Undead to a unit that does not possess it by default. As a result, the Ghouls will remain the only unit to possess this ability during the game.
Note however that a similar ability - Life Drain - can be bestowed to units that do not possess it. One of the side-effects of Life Drain is to create new Undead units out of slain enemies, though it operates a little differently than Create Undead. Read the Life Drain article for more information.