Secondary skill
Secondary skills are beneficial qualities of heroes. There are 28 different secondary skills and each one has three levels: basic, advanced and expert. Each level increases the capability of the secondary skill making it more influential. Typically in custom scenarios heroes start with either two secondary skills at basic level or one at advanced level. Each hero can have up to eight secondary skills.
Secondary skills are commonly considered to belong to three categories: combat skills, magic skills and adventure skills, combat skills affecting combat directly (f.e. Offense, Armorer, or Tactics), magic skills affecting hero's ability to cast spells (e.g. Schools of magic) and adventure skills providing hero with various benefits on the adventure map (such as Estates or Logistics).
Once secondary skill is learned, it cannot be removed. As a result, secondary skill choices on level-ups are among the most important decisions in the game.
Secondary skill advancement rules[edit | hide | hide all]
If a hero does not already possess eight secondary skills, they get an offer of two different skills during level-up. The first offer is a randomly selected skill they already have at Basic or Advanced level. The second offer is random, with weighed probabilities based on the skill probability tables for each hero class. If a hero already does not have any secondary skill at Basic or Advanced level, they are offered two new skills, again randomly, based on the weighed probabilities. If a hero already has all eight secondary skills, they are offered an advancement of two skills they already possess at Basic or Advanced level, randomly, again, based on the hero class secondary skill probabilities. If a hero has a skill banned for their class (e.g. Water Magic on Barbarians), that skills weight is considered to be 1.
There are a few other ways to acquire secondary skills. They can be learned from scholars, witch huts, universities, and seafaring acadamies on the adventure map. Conflux 
has a special building, magic university, that can teach any number of the four schools of magic. Additionally, heroes can learn secondary skills from events and Pandora's Boxes.
The random seed for offering skills is separate for every hero and is fixed at the start of the scenario, including heroes that had not been hired by any player yet. Therefore, even when reloading, hiring, re-hiring and levelling your heroes in a different order, they will still be offered the same sequence of skills upon reaching the next level. The only option to change these is by obtaining a secondary skill outside of normal levelling, e.g. from Witch Hut or Scholar. Every choice affects future upgrade options, so upon replaying the same saved game any alterations can lead to a vastly different result.
Heroes are also guaranteed to be offered Wisdom and school of magic every few levels: Wisdom will be offered at level 6 for Might heroes, and at level 3 for Magic heroes if it was not offered before. It will be offered again from whenever it was offered at most 6 levels later for Might heroes, and at most 3 levels later for Magic heroes. The same applies to one of the schools of magic every 4 levels for Might heroes and every 3 levels for Magic heroes. The only exception is the Elementalist class, to which are considered Might heroes by the levelling system. In HotA 
, Elementalists correctly level up in the same manner as other Magic heroes.
This algorithm can be summed as follows:
- Create two categories of skills: Those the hero has at the Basic/Advanced level, and those the hero has not learned yet. Ignore Expert level skills, globally banned skills (e.g. Navigation on land-locked maps) and skills banned for the specific class (e.g. Necromancy for all heroes from factions other than Necropolis).
- If one of the categories is empty, offer two skills from the other category; if there is only one skill to offer, it will be forcefully added to the hero; if there is none, level-up with gaining only primary skill.
- If the hero is guaranteed to get offered Wisdom (every 3 levels for Magic Heroes and every 6 levels for Might heroes) or a School of Magic (every 3 levels for Magic heroes and every 4 levels for Might heroes), offer them the appropriate skill. This rule applies to both offers (left and right skill). Wisdom has the higher priority than the Schools of Magic. The exact School of Magic offered is randomly chosen based on the relative probabilities (see 4.)
- For each slot, if the skill is not guaranteed to the rule above, select the skill based on the weighed probability, according to the hero class. If the hero's class is banned from obtaining a specific skill but the hero has it, consider the weight to be equal to 1.
- If a Wisdom or School of Magic was offered (either by chance or by force), reset their respective counter.
Heroes starting with more than 1000 experience points (above level 1), such as those from Prison, are assumed to have always selected the left-hand skill option during their fictitious level-ups, meaning they will prioritize upgrading their existing skills over learning new ones.
Frequency Across All Hero Classes[edit | hide]
The following chart is a chart for all hero classes and what skills are the most and least common in the game; the percentage represents roughly the frequency a skill is offered. Calculating the average frequency at which a skill is offered in a category is simple; each hero has probabilities to be offered a skill in increments of 1/112. Taking Necromancy as a simple example, all heroes except for Necropolis heroes have a 0/112 chance of being offered it; while both Necropolis hero classes have a 10/112 chance of being offered it (if not starting with it). This would bring the sum of lots to 20. Given that there are 18 hero classes, 18 x 112 = 2016 lots in total calculation. Thus, we can divide 20 by 2016 to get the frequency the skill is offered among all hero classes, which is roughly 0.99%, making it the rarest naturally offered skill in the game.
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| Secondary skill | All Classes |
Might Classes |
Magic Classes |
Good Classes |
Neutral Classes |
Evil Classes |
|---|---|---|---|---|---|---|
 Air Magic |
2.5 | 2.0 | 3.0 | 3.0 | 2.7 | 1.9 |
 Archery |
4.2 | 5.2 | 2.7 | 4.2 | 4.6 | 3.7 |
 Armorer |
4.1 | 5.9 | 2.3 | 4.2 | 4.5 | 3.7 |
 Artillery |
3.7 | 5.0 | 1.8 | 2.8 | 4.5 | 3.9 |
 Ballistics |
5.4 | 6.2 | 4.7 | 4.5 | 6.1 | 5.7 |
 Diplomacy |
2.9 | 2.4 | 3.5 | 3.9 | 1.9 | 3.0 |
 Eagle Eye |
4.2 | 2.9 | 6.3 | 4.2 | 4.2 | 4.2 |
 Earth Magic |
3.3 | 2.7 | 3.9 | 2.7 | 3.1 | 4.0 |
 Estates |
2.5 | 2.3 | 2.6 | 3.4 | 1.6 | 2.5 |
 Fire Magic |
2.1 | 1.4 | 2.9 | 1.0 | 2.5 | 2.8 |
 First Aid |
3.4 | 2.5 | 5.1 | 4.6 | 3.6 | 2.1 |
 Intelligence |
4.0 | 2.4 | 6.3 | 4.5 | 3.4 | 4.2 |
 Leadership |
3.2 | 4.1 | 2.1 | 4.0 | 3.1 | 2.4 |
 Learning |
4.1 | 4.2 | 3.6 | 4.5 | 4.2 | 3.6 |
 Logistics |
4.8 | 5.7 | 3.4 | 4.0 | 5.5 | 4.8 |
 Luck |
2.6 | 2.4 | 3.1 | 4.3 | 2.2 | 1.3 |
 Mysticism |
4.4 | 3.1 | 6.2 | 4.0 | 4.2 | 4.9 |
 Navigation |
3.7 | 4.6 | 2.9 | 3.3 | 3.7 | 4.0 |
 Necromancy |
1.0 | 1.0 | 1.0 | 0.0 | 0.0 | 3.0 |
 Offense |
4.5 | 5.8 | 2.5 | 3.6 | 5.2 | 4.6 |
 Pathfinding |
3.9 | 4.6 | 2.9 | 3.6 | 4.5 | 3.7 |
 Resistance |
3.0 | 4.7 | 1.1 | 3.3 | 2.5 | 3.1 |
 Scholar |
3.7 | 1.9 | 6.1 | 4.2 | 3.3 | 3.6 |
 Scouting |
3.6 | 4.6 | 2.2 | 3.3 | 4.3 | 3.1 |
 Sorcery |
4.0 | 2.5 | 6.3 | 3.7 | 3.7 | 4.6 |
 Tactics |
3.8 | 5.2 | 1.8 | 3.0 | 4.3 | 4.2 |
 Water Magic |
2.3 | 1.8 | 3.0 | 3.0 | 2.4 | 1.6 |
 Wisdom |
5.2 | 3.7 | 7.2 | 5.5 | 4.2 | 5.8 |
In Horn of the Abyss, the calculations are trickier, as each hero class does not have an exact 112 lots of skills, but rather each hero class has 112 to 121 lots of all skills. Things are further complicated by Resistance being banned by default on all maps and templates and consequently the vast majority of games played not having it in the lots. Furthermore, Navigation is also banned by default on all random map templates without water (and the vast majority of templates were created with the "None" water setting in mind, as with water, border guards and other barriers can often be bypassed). Removing both Navigation and Resistance from the lots make the lots range from 102 to 111.
In this chart, the sum of each column will be over 100%, as Navigation and Resistance are not counted, and their listed percentages are not their true percentages, but are there only to compare to other skills.
An example calculation: on average, each hero class has 107 lots if Resistance and Navigation are both disabled. There are currently (as of 1.6.1) 20 hero classes in Horn of the Abyss, which makes the grand sum of lots 107 x 20 = 2140. Interference has 54 lots across all hero classes, making its percent 54 / 2140 ≈ 2.52%. Resistance has 68 lots across all hero classes, making its percent 68 / 2140 ≈ 3.18%; but this is only a comparative value, rather than a true percentage, as the chance to get Resistance if it is disabled is 0. A real value could be computed if Resistance was enabled and Interference disabled, or if both were enabled; however enabling or disabling any skill will change the grand sum and thus change the percentages of all skills. For example, if all skills are enabled, the grand sum becomes 2294. Interference's average chances becomes 54 / 2294 ≈ 2.35%; while Resistance's average chances becomes 68 / 2294 ≈ 2.96%; while Artillery's chances go from roughly 4.63% to 4.32%.
The chart below assumes Resistance and Navigation are both disabled and the figures given for those skills are only for comparison rather than true percentages.
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| Secondary skill | All Classes |
Might Classes |
Magic Classes |
Good Classes |
Neutral Classes |
Evil Classes |
|---|---|---|---|---|---|---|
| Air Magic |
2.8 | 2.1 | 3.5 | 3.1 | 3.2 | 2.0 |
| Archery |
4.6 | 6.2 | 3.1 | 4.3 | 5.4 | 3.9 |
| Armorer |
4.0 | 5.8 | 2.2 | 4.3 | 3.9 | 3.9 |
| Artillery |
3.8 | 5.8 | 1.8 | 2.9 | 4.2 | 4.1 |
| Ballistics |
5.4 | 6.3 | 4.6 | 4.6 | 5.6 | 5.9 |
| Diplomacy |
3.1 | 2.7 | 3.5 | 4.0 | 2.3 | 3.1 |
| Eagle Eye |
4.2 | 2.3 | 6.1 | 4.3 | 4.0 | 4.4 |
| Earth Magic |
3.5 | 2.9 | 4.1 | 2.8 | 3.5 | 4.2 |
| Estates |
2.7 | 2.7 | 2.6 | 3.6 | 2.0 | 2.7 |
| Fire Magic |
2.2 | 1.5 | 2.9 | 1.1 | 2.5 | 3.0 |
| First Aid |
3.5 | 1.9 | 5.1 | 4.8 | 3.5 | 2.2 |
| Intelligence |
4.3 | 2.0 | 6.6 | 4.6 | 4.0 | 4.4 |
 Interference |
2.5 | 4.9 | 0.2 | 2.9 | 2.1 | 2.7 |
| Leadership |
3.4 | 4.6 | 2.1 | 4.2 | 3.4 | 2.5 |
| Learning |
4.1 | 4.5 | 3.7 | 4.6 | 4.0 | 3.7 |
| Logistics |
4.9 | 6.4 | 3.5 | 4.2 | 5.4 | 5.0 |
| Luck |
3.0 | 2.7 | 3.3 | 4.5 | 3.1 | 1.4 |
| Mysticism |
4.3 | 2.5 | 6.1 | 4.2 | 3.8 | 5.1 |
| Navigation |
4.0 | 4.8 | 3.3 | 3.4 | 4.3 | 4.2 |
| Necromancy |
0.9 | 0.9 | 0.9 | 0.0 | 0.0 | 3.1 |
| Offense |
4.8 | 6.9 | 2.7 | 3.7 | 5.6 | 4.8 |
| Pathfinding |
4.3 | 5.4 | 3.3 | 3.7 | 5.2 | 3.9 |
| Resistance |
3.2 | 4.9 | 1.5 | 3.4 | 2.9 | 3.3 |
| Scholar |
3.7 | 1.3 | 6.2 | 4.3 | 3.3 | 3.7 |
| Scouting |
3.6 | 5.1 | 2.2 | 3.4 | 4.1 | 3.3 |
| Sorcery |
4.2 | 1.9 | 6.4 | 3.9 | 3.9 | 4.8 |
| Tactics |
4.1 | 6.1 | 2.1 | 3.1 | 4.6 | 4.4 |
| Water Magic |
2.7 | 1.8 | 3.6 | 3.1 | 3.2 | 1.7 |
| Wisdom |
5.3 | 3.0 | 7.6 | 5.7 | 4.3 | 6.1 |