Skill
From Ymirheim Wiki
Skills is one of the ways the players interact with the monsters and other players during PvE or PvP activities. In Ymirheim every class has its own set of skills. Some skills can be shared, which means certain skills can be used outside their original class. There is a wide verity of skills in the game: offensive, defensive, buffs, debuffs. Skills usually consume a resource called mana and rage. To learn and level up skills, the players have to use skill books.