Will
From NsdWiki
Expoint Cost: 1
Will reflects a character's inner resilience and power of mind over matter. Willpower resists supernatural forces throughout Gaeis. A Will point can be used in game to allow a character to counter certain magical or supernatural effects. Like Might, once a point of will is used, it is gone forever. Magic-users may call upon their Will when Mana is spent, for spending a point of Will allows the spellcaster to use his body as fuel, exchanging 5 Health Points where 1 mana would be due (this is described further on in the chapter on Magic). You may not have more than 5 points of Will at any one time.