Heroes II added the Necromancer and Wizard factions, joining the Knight, Barbarian, Sorceress, and Warlock from the first game. Heroes II introduced several new features that have since become standard for the series. First among them is the ability for heroes to gain special abilities. Each hero can possess up to eight different secondary skills out of fourteen available. Once gained, a skill can be developed from Basic to Advanced and Expert levels. For example, the Wisdom skill allows a hero to learn spells of level 3 and higher, while the Logistics skill increases the hero's movement ability over land. In Heroes I, heroes had a single fixed special ability according to their class.