Heroic is a new type of game mode introduced in Star Warfare 2. Heroic immediately starts ramping up the difficulty for the aliens and bosses and makes them deal more damage then ever before. Heroic also grants new achievements and each alien killed in heroic is worth much more gold.
Missions in heroic also become much more stronger and you will have to defeat more aliens, defend against much more aliens, and take longer to survive each level. Heroic is not for the faint of heart and is not recommended for people with low-tier armor or weapons as those can have literally no effect on the bosses or aliens in heroic.
Aliens that are suppose to appear later in the game also appear in earlier levels such as Banished Battlefield making survival in the early levels harder. Killing heroic bosses also grant the player certain titles. Heroic is unlocked after you beat Cerberlisk in normal mode.