Casting Magic in Combat

Description
Magic attacks are usually unaffected by armor, unless that armor is a magical deterrent, which is somewhat rare. Defense also does not affect magical attacks usually, but some directed attacks are affected by Defense, and can also be dodged, and so the the Defense score minus Armor can be used to subtract dice from an attack in these instances. Usually, offensive magic does lethal damage, but many Water, Earth, and Wind techniques do levels of Bashing damage in addition to other status or secondary effects like knocking enemies prone or causing penalties.

Casting magic works as such:"Cast: Gnosis (X) + Intelligence 󰀀 = X + Y"Gnosis denotes the Rank of spells accessible to the caster. Intelligence is the raw processing power of the caster's mind, and so together, make up the dice pool for casting magic.

Difficulty and Control
The Rank of a spell denotes its difficulty. There are 6 levels, from lowest to highest: E, D, C, B, A, and S. the level of rank corresponds with the number that the caster has to exceed to be successful when they roll dice. The amount of dice in their dice pool dictates the chances of them being successful (rolling to exceed the target number), and can be subtracted from and added to for a variety of reasons.

Examples for adding dice to dice pools: Examples for subtracting dice from dice pools: A caster attempting to cast at their highest ability is going to have a harder time than casting something they have much more control over. If their Gnosis is 3, then they have access to Rank C spells, but it means that they must make a 4 or higher to succeed in casting Rank C spells. If they have an Intelligence of 2, then their dice pool is 5, and must roll 5 dice wherein only 3 of the numbers are valid (4, 5, and 6). If they attempted a lower level spell, like Rank E, then they must roll 5 dice wherein 5 of the numbers were valid (2, 3, 4, 5, 6), and the chances of getting any success, including an exceptional success, is much more likely.
 * Willpower (+3)
 * Elemental Advantage (+1-3)
 * Charging (+1/round = to Resolve)
 * Damage (-1 for every Lethal)
 * Armor (-1 for every point of Armor that resists magic)
 * Wards (-1 for every point of Ward, but must be replenished or regenerates x/round)

Successively higher-ranked spells are increasingly more difficult to cast. This also means that their potential Margin of Success (MoS) is necessarily less likely with a higher-level spell, but with the tradeoff being a generally more powerful attack which mitigates this and is usually worth it, when all things are equal--which is not alway the case. In certain circumstances, it might be more worth it to cast an easier spell than a harder one.

Spell damage
Like weapons, a typical spell can do Bashing or Lethal damage--usually shown in the formula XL (+ XL automatic) or similar. Some of the most basic spells might show 0B or 0L. In this case, the spell itself doesn't impart any additional damage nor any automatic damage, but only imparts the MoS of the caster's roll in that type of damage. For example, a caster might want to cast Flamespout, which is 0L. It is Rank E, and so the caster must make a 2, 3, 4, 5, or 6. The Caster's roll is Gnosis (2) + Intelligence (3) = 5 to make a 2 or above. They roll, and their highest die is a 6, an MoS of 5, so the attack does 5L.

Let's say the same caster wants to cast Ring of Fire, which is D Rank, 1L (+ 1L automatic). It is denoted in lethal, so all damage is lethal in this attack. He needs to beat a 2, rolls and gets a 3, an MoS of 1, so the spell does 1L due to the spell having a quality that always does at least 1 Lethal, the MoS of Lethal, which is also 1 in this case, and 1 automatic Lethal, which is unavoidable, even if one dodges or blocks. In total, the attack did 3L. If he had rolled another 6, then the MoS would have been, 4, meaning the attack did 1L, + the MoS in Lethal (4), + another automatic 1 Lethal, so 6L in total. This is because circumstances of casting can affect the damage the caster inflicts but some spells have a base amount of damage or effect that they can do, which increases as they become more complex.

Damage
Damage is the bane of casters, and makes it very difficult to properly cast magic, especially higher-level magic where finesse and mental acuity is important. Sustaining some damage might force a caster to downgrade the Rank of spells they're trying to use in order to be more likely to be successful, (ultimately making them less threatening), break concentration, or retreat. Some spells require a caster maintain concentration, and so damage both reduces their casting dice pool as well as their Perception dice pools. It is for this reason that military casters are trained to be be able to cast even if injured, and also why some casters prefer to forgo greater destructive force for the ability to more assuredly injure or rattle, thereby neutralizing the threat more quickly.

Wards
Wards are like armor, but they negate successful attacks by soaking damage, as well as subtracting from dice pools, usually -1 for every point of Ward, but they must be replenished or in very strong cases, regenerate x/round. For example:

A caster has Gnosis (5) + Intelligence (4) = 9. She tries to cast Flame Pillar, a C Rank spell, at a target who has a +2 Ward. She must roll 9-2 = 7 dice and get a  4 or higher. The spell does  0L (+ 1L automatic), meaning that her damage is Lethal, and does at least 1 Lethal automatically because there is something unavoidable about it--like a blast radius.

She rolls 7 dice, and gets a 5, and MoS of 2. The Flame Pillar emerges from a wall and strikes at the target unawares, who does not dodge, and would normally do 2 Lethal, but the +2 Ward soaks that damage--but it does not soak the +1 automatic Lethal. It also isn't a Ward that recovers, meaning the next cast there is no magical protection. Wards are often cast by spellcasters on themselves and others, to give them extra defense in a pinch, but very rarely do they soak very much damage or automatically recharge. That takes magnitudes more energy, and is often done for structures of import or warriors of incredible power or wealth. Or both.

Buffs
Similar in nature to Wards are Buffs, which represent magnitudes of power: D6s to D10s, for example, giving a caster the ability to have successes higher than 6--all the way to 10. What pushes somebody from D6s to D10s is circumstantial, but usually a regular Buff spells and potions can do it for most casters, allowing the chances of exceptional successes to rise, as well as the ability to simply compete with much more powerful, supernatural entities and beings.

For example, powerful barriers and defenses might withstand even A Rank spells even if they're cast by exceptional casters. Those that do require that you roll at least an 8, which is impossible unless you are strengthened through a Buff. Buffs don't just affect magic either, but they affect mundane rolls as well, and it allows some people supernaturally withstand things like a direct hit by artillery fire, or breaking down a castle wall unarmed