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. 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.
If a hero does not already posses eight secondary skills, he gets an offer of two different skill during level-up. The first offer is a skill he already posses but which is not yet at expert level. The second offer is random, but the probabilities of the skills offered are dependable of the hero's class. If a hero has already all secondary skills at expert level, both offers are random. If a hero already has eight secondary skills, both offers are random but within the skills hero has.
Secondary skills are divided into three categories: combat skills, magic skills and adventure skills. Combat skills affect directly to combat capabilities of creatures under hero's command.; magic skills affect hero's abilities to cast spells; and adventure skills improves hero's adventure map qualities.