The hero gains levels twice as fast, for instance by putting a new level cutoff between each existing set of cutoffs (10 for level 1’s 0 to 20, 30 for level 2’s 20 to 40, etc). However, the player must choose with each level gained whether to take most of the effects of gaining an experience level - HP and Pw increases, etc, but NOT a skill slot - or a new skill slot.