Willpower (self discipline)
Pick one spell that you know. That spell is now tattooed on your body. All costs to cast this spell is one lower in magic points.
Pick a second spell to also be tatooed. When casting tattooed spells the mage can spend both health and spell points to fuel them. If health is used the spell power is at +1 for resisting the spell.
Master: Pick a third spell you know to be a tattoo. If all health is used to cast a tattooed spell the spell is at +2 to spell power (total) for the casting. And add +1d6 to the spells damage if it's a damaging spell.