HD is hit dice... As characters this is the same as your level. So we will be level four and have four hit dice. It's supposed to be less confusing as you could be a level3 barbarian and level 1 rogue and have four HD.<br/><br/>BAB is base attack bonus. It is listed on your character-chart thing. As a fighter, it goes up by one per level. Wizards, for example, get +1 BAB every other level. So their hit dice is much greater than their BAB.<br/><br/>Thus that feat is not good for a fighter as BAB=HD for them.<br/><br/>Ambrose