- Heroes in Heroes 3

well, imagine that by level 20, you have 130% more attack (with an Attack expert).

A specialist in attack receives +5% to damage per level (not to attack). That is, if he has an Attack expert, which gives a damage bonus equal to 30%, then by level twenty, this bonus will double and become equal to 60% (of the initial damage), but not 130%. In other words, the damage bonus increases, not the damage itself.