Heroes 5.5 WarGame Edition - Tactical Edition.

Example of Power (note that the special skill applies only to certain units; heroes do not have this skill):

Chaos Power: Enemy Chaos magic spells are weakened: they are always cast at skill level 0 and with 90% casting chance (30% casting chance for special skill spells). The hero receives +2 to attack for each developed/expert Chaos Power level, if the enemy hero has not developed a developed/expert Chaos Magic skill.

The meaning of separating the weakening effect and combat bonuses is simple: we must be able to counter a school with a relatively small number of skill points (in this case, only 1 for the base skill + 0 to 3 for the abilities). The remaining part of the skill and abilities is invested in combat bonuses. But if we simply give good combat bonuses, the Power will become too strong. After all, it would be possible to completely negate a large number of levels that the opponent has invested in a particular school, and in return, receive bonuses. Therefore, the neutralization is mutual:
- either you don't take combat bonuses (you don't develop the skill to developed/expert), and then if you don't guess the school, you will be at a disadvantage, but a small one (and if you guess, the opponent will be at a small disadvantage)
- or you take combat bonuses, but then if you guess the school, and the opponent has invested heavily in it, both will suffer (you will be left without these bonuses)
Finally, combat bonuses will be very useful in breaking through defenses (where simple weakening effects simply fail).

Banning to skill level 0 looks scary, but in reality, the effect is on average no stronger than, say, "-30% damage from Chaos." This is due to the fact that the dependence of the strength of spells on the skill level is significantly reduced (each skill level strengthens the spell by an average of 0-30%).