My magic "system" for Mythic RPG is pseudo-realistic. The magic that one can tap into channels from the caster's body. Your "biomatrix" or "positive/negative energy" or the energy resonating from your "spirit/soul" acts as the focus/instrument needed to convert the surrounding/ever-present mana that exists into "magic". You may think: "well, doesn't that mean /everybody/ can use magic then?" Yes and no. Yes, everyone can use magic, but it takes training to understand the pseudo-real components of even trying to light a candle with your fingertip...or mind if you're a psychokinetic. And no, not everyone can use magic. Creatures of lower intelligence will never have the mental capacity to understand how convert mana into magic.

My magic "system" for Mythic RPG is pseudo-realistic. The magic that one can tap into channels from the caster's body. Your "biomatrix" or "positive/negative energy" or the energy resonating from your "spirit/soul" acts as the focus/instrument needed to convert the surrounding/ever-present mana that exists into "magic". You may think: "well, doesn't that mean /everybody/ can use magic then?" Yes and no. Yes, everyone can use magic, but it takes training to understand the pseudo-real components of even trying to light a candle with your fingertip...or mind if you're a psychokinetic. And no, not everyone can use magic. Creatures of lower intelligence will never have the mental capacity to understand how convert mana into magic.

I will explain thoroughly. Still: please ask questions for further clarification.

1. Roll to see if you can conjure the spell. The Acting Rank (AR) is your [magical ability] vs the Difficulty Rank (DR) of level of the spell you are trying to conjure.
Example: If you are trying to conjure a fireball in your hand, from your fingertip(s), mouth, eyes, etc. Its base DR is Below Average (a Level 3 spell). Let's say your AR is Above Average (level 5). Looking on the Fate Chart, you'd have a 80% chance at conjuring a single fireball.

You can make this fireball stronger /or/ weaker. Stronger will mean the success percentage will decrease. Weaker will mean the success percentage will increase.

For this example let's say your foe has the Toughness of High. Just /one/ rank above your [magical ability]. You're are definitely going to want your fireball to be stronger. Unless....you're a pacifist? Maybe a weaker fireball would be less lethal? Maybe force the creature to flee or see reason in your early (failed) attempt at Diplomacy? But for this example you are dealing lethal wounds. Your success percentage of being able to conjure a fireball with the DR of High and your AR is Above Average is 45%. What are your 4 possible outcomes?
a) Yes- You succeed at conjure the fireball.
b) No - The spell fizzles out.
c) Exceptional Yes (Critical Yes/Nat 20)- Flash Fire: you get a +1RS on the current rank of the fire.
d) Exceptional No (Critical No/Nat 1)- The fireball explodes and you or your ally is harmed by the fire.

What about rank modifiers?
a) As stated before: +1DR each time you're trying to make a stronger fire.
b) Distracted: +1DR
c) First try: -1AR

2. Fire/shoot/throw your spell, if you succeeded in conjuring the spell.

3. Fatigue.

How long does it take for the spellcaster to become fatigued from casting spells?
a) I feel that strongly depends on the spell's requirements. If your [magical ability's] rank is Incredible (level 8) then you could probably throw...15 level 3 fireballs back-to-back and start to feel "winded" after the 15th fireball fires.

You can attempt powerful spells at a low-level, but do you even have a chance to succeed? Failure could mean the spell backfiring and killing you OR you immediately die from extreme fatigue.

Do they have spell slots and/or have to prepare spells? If not, then how do you know what spells you can use?
a) No spell slot or prepared spells. You judge your character's spell knowledge based on their history with magic.
b) Example: My lady's PC has two magically imbued parents. Her father is gifted with Chlorokinesis and her mother with Fire Sorcery. She was raised by her mother, so she naturally had a higher rank with Fire Sorcery. While the Chlorokinetic ability being innate, it wasn't too low, because she practiced with it when she could. Her Fire Sorcery training gave her PC a good set of attack spells, but she never learned how to shape the fire into humanlike objects i.e. a sword, shield, or armor. She can use fire breath or fireball, but had to learn from a master spellcaster how to shape her magic into a sword and shield.