SG: The Cost of Magic
Casting magic is taxing. Whether you are channeling it from a higher power, or calling upon personal reserves of power, all that magic coursing through you is stimulating — and exhausting.
Each time you successfully cast a spell, you should take one point of mental stress. If you have no mental stress boxes open, you can instead take a consequence. And yes, you can take yourself out doing too much magic. However, when you succeed with style, you do not have to mark off that mental stress box.
If you tie a difficulty to overcome, but wish to succeed at a minor cost, you must take an additional point of stress, but you may choose to mark off either a physical stress box or a mental stress box.
If you fail, but wish to success at a significant cost, you must take a magic-related consequence, in addition to whatever else the GM might decide makes sense.
This means that the Will skill is often very important to spell slinging characters because greater Will grants them the stamina to allow the use of more magic.
When casting spells outside of combat, the cost of stress doesn’t mean very much because it’s trivial to recover that. Therefore, the GM should consider other costs to casting spells when the mage has the luxuries of time and safety. Smart spellcasters will use safe refuges and spend the time needed to create many aspects with which to improve magic skill rolls. This means complicated and powerful effects become possible.
However, magic always carries a price. There is always some kind of sacrifice involved. A player wishing to pull off a powerful spell should think carefully and suggest sacrifices that make sense, or else be satisfied with whatever cost the GM thinks appropriate.
Magic-using characters can take a stunt for a Magical Skill that reflects a particular affinity for that kind of magic. This affinity negates the need for a character to pay a point of mental stress when using that particular skill to cast a spell.
For example, if your character takes a stunt like Earth Mastery, he can define it to say that he pays no mental stress to cast spells using Earth Magic.
This does not negate the need to pay a minor or significant cost to succeed when you tie or fail an Overcome or Create an Advantage action.
Next: Magical Skills