The Battle Booster (also known as BB) is the setting that determines how much Energy is used per battle in the Battle Arena. It also multiplies the gains (and losses) of fought battles. The normal maximum is (7 + Commander Level/10). VIC Status gives a static +2 to your max booster. You can increase your max booster with command points in the efficiency skill tree but not higher than (maxE/25). The maximum BB is always rounded up to the nearest decimal. If you use a BB that is lower than the maximum, you can only select values rounded to the nearest unit from the dropdwon menu.