Even though Action Power is capped at 299, there appears to be no limit to how much it can drop, unless it is by being hit by the Spearman's Lightning Spear in which the lowest it can drop from it is -50 Action Power. Some abilities such as Deadly Strike can drop the character's Action Power deep into the negative. A character can still use an action if their turn is active even if it exceeds their current Action Power. For example: A Swordsman with 100 Action Power moves to a new spot (-50 Action Power) and then uses his Flame Sword skill (-150 Action Power) he is now left with -100 Action Power.