Use Willpower as needed to quickly move a unit out of trouble, activate a special skill, and add damage to attacks. It is restored to full before the next battle. Use the right-most icon of the Horn symbol at the top of the screen to give one unit of willpower to your current unit. Because the Horn only holds a set amount of Willpower, use it regularly so it will not be wasted. Characters with useful special abilities (for example, Yrsa's area-of-effect attack) require more willpower. A maxed out Exertion stat allows units such as Varl to put more Willpower into each action.