Horror marks can be applied to both units and commanders by various effects, and will cause Horrors to have a random chance to attack the unit in an assassination setting at the beginning of every turn. In addition, horror marked targets are preferred targets for any horrors spawned in normal battles. A unit that is horror marked will have the icon displayed alongside its other abilities.

Horror marks stack: that is to say that a unit which is marked multiple times has a more severe mark and will be the target of more frequent and stronger horror attacks. There is currently no way to tell how badly horror marked any given unit is.

There is no way to remove a horror mark entirely. The only exception is units that may return once slain - for them Horror Marks are reduced every turn spent dead, down to 1 mark.

Mindless commanders or those who are Slave Vessels are excempt from the attacks discussed on this page.

A unit can gain Horror marks in a number of ways:

• Guaranteed when casting Hell Power, when affected by Horror Mark (1) or the primary effect Astral Geyser (2)
• Chance per turn when holding a tainted magic item (1)
• Chance per turn when in a province with certain magic sites.
• Chance per turn when in a province protected by the Dome of Corruption
• 1 or 2 when empowering in Blood: 7.5% per level of blood prior to empowerment, or 25% if the commander had no blood levels¹⁾.
• Chance when casting certain spells such as Send Horror
• Certain global events, such as that caused by the Vale of Infinite Horror being discovered (a certain percentage of units must make a MR check vs 16, -1 per two astral levels, or gain one mark)

There is no way to remove a horror mark entirely, though for units that may return once slain, horror marks are reduced every turn spent dead. This is always 10% of their mark count per turn, rounding down. The mark count will be reduced by a minimum of 1 mark per turn with the only exception that it cannot reduce a unit's marks to 0.

When hosting a turn, there are three different distinctions used by the game when deciding to send a horror assassination to a marked commander. First, the game considers "normal" horror assassinations. After this, there are then additional separate chances to send Umor - Eater of Gods to marked pretenders and Rarku - Hunter of Heroes to creatures in the Hall of Fame.

The attack rate of horrors is dependent on several factors, and is calculated by the game as follows²⁾:

• Get the count of Horror Marks on the affected commander. If this number is greater than 100, consider it as if it were 100.
• The "Attractiveness" value is first calculated as (mark count * 5) + 1.
• If the unit is holding a cursed item, add an additional mark count * 5.
• The final attractiveness is calculated as:

• Generate a random number between 0 and 999. If the random number is less than the calculated attractiveness value, the commander is attacked by a lesser horror.

The resulting lesser horror attack is subject to the usual upgrading process and multiplicity described in the Horror article.

Due to the multiplication, the effect of scales on the attack rate is largely negligible unless the Global Horror Level increases dramatically.

In a normal game state with a Global Horror Level of 1, Horror Marks have an approximately 0.5% per mark per turn chance to produce a horror attack, which is then doubled if the commander has a cursed item, to a maximum of 50% at 100+ marks. This is consistent with experimental data ³⁾

Rarku - Hunter of Heroes seeks out commanders with heroic abilities or that are in the Hall of Fame. As with the above, Mindless commanders are unaffected.