Spell Casting

Spellcasting is the act of turning mana into a magical effect through intent. While there are many kinds of magic, a spell refers specifically to effects that follow established casting rules—requiring mana, verbal components, and using a god as a conduit.
  Spells are reliable, reproducible phenomena shaped through words, gestures, and sometimes materials. Though divine conduits plays a role in how spells are executed, the act of spellcasting is widely understood, studied, and practiced across nearly all fields of magic.
 

Mana & Casting Level

All casters begin with a base mana pool of 100 and a casting level of 1. Mana is the raw resource used to cast spells, while casting level determines how much mana can be spent in a single magical instance.
  A magical instance refers to any single event in which mana is expended to create a magical effect. This includes spells, augmentations, or enhancements used at the same time. The combined mana cost of all effects used in the same moment must not exceed your casting level. For example, casting a level 3 spell alongside a 2-mana enhancement requires a casting level of at least 5.
  If the total cost exceeds that limit or your remaining mana, the casting fails and nothing happens. Effects that modify a spell without drawing mana at the time of casting, such as Amplify Magic, are not bound by this restriction and can be applied freely.
  Casting level increases with your overall level. Buffs and magical tools can temporarily raise your casting level, but this does not allow you to learn or prepare spells that are a higher level than your natural casting level.
 

Spell Level & Upcasting

Each spell has a level from 1 to 9, and its mana cost is equal to its level. A level 3 spell costs 3 mana to cast, a level 5 spell costs 5 mana, and so on. You can only cast spells if their level does not exceed your current casting level.   Most spells can be upcast, meaning they are cast at a higher level than required. Upcasting increases the mana cost and enhances the spell’s effects, such as improving damage, range, or duration. The benefits of upcasting vary by spell.   9th level spells are the highest that can be naturally cast by mortals. Some effects, such as an arcane focus, bounded magic, or divine contracts, can temporarily allow for casting beyond this limit. Spells above level 9 do exist, but they are typically restricted to gods and are not available through normal means.   Downcasting is possible, though rarely used. Casting a spell below its intended level usually results in a weaker or incomplete effect and is considered inefficient in most cases.  

Spell Types

Spells come in several forms, each with specific timing and component requirements. Most spells are cast as either an action or a bonus action, depending on their structure.   Spells that require only a verbal component can be cast as a bonus action. Spells that also require a somatic component must be cast as a full action. Some spells also require a material component if they involve the creation or manipulation of a physical object. All spells require a verbal component. This means silence, deafening noise, vacuums, or anything that prevents the caster from speaking will block most spellcasting entirely.   Reaction spells activate instantly in response to specific triggers, but they still require a verbal component and a Reaction to function. Common triggers include being targeted by an attack, taking damage, or witnessing another creature's movement or spell.   Ritual spells are long-form magic that take minutes or hours to complete. These spells allow casters to pour mana into them gradually, up to their casting level per turn. Rituals are most commonly used for summoning, divination, and divine communication, such as prayer.   Passive spells create ongoing effects that persist for a set duration. These typically include enhancements, protective wards, or status effects. They are cast normally and follow the same rules for components and casting time as other spells.  

Smites

Smites are a unique spell type that are cast at the same time as a melee weapon attack. When used on a full action attack, a smite can be applied without consuming anything beyond its mana cost. Smiting on a bonus action attack is still possible, but it requires an additional bonus action to cast the smite, making it inaccessible in most cases.   It is possible to apply multiple smites to a single attack if each smite is a different spell. Each additional smite consumes a separate bonus action and must fit within your casting level. For example, using two level 2 smites in the same attack would require a casting level of at least 4. However, most smite spells require concentration, so only one active smite can use concentration.   Adding a smite to an attack transforms the strike into a spell attack. You may choose to use either your weapon attack modifier or your spellcasting attack modifier when making the roll, whichever is higher.  

Concentration

Some spells require concentration to maintain their effects over time. A caster can only concentrate on one spell at a time. Starting a new concentration spell immediately ends the previous one.   If a concentrating caster takes damage to their hit points, they must make a Constitution saving throw to maintain the spell. The difficulty of this save is either 10 or half the damage taken, whichever is higher. Damage absorbed by temporary hit points or similar effects does not trigger this check.   A caster can choose to end concentration at any time without penalty. Concentration also ends automatically if the caster becomes unconscious, dies, or the spells duration ends.
 

Learning & Memorizing Spells

All spells must be memorized before they can be cast. This process takes place during a long rest, at which point a caster can freely rotate which spells they wish to keep in mind. Outside of special cases like wizard spellbooks, spells cannot be swapped mid-day.   There is a hard limit to how many spells a caster can hold in memory at one time, based on the spells level. This memory limit applies regardless of the source of the spell. Most casters never reach this limit, but it becomes relevant for those with wide access to divine spell lists or extensive personal study.   Spells can be forgotten at any time to free up memory space, though doing so must be done on a long rest. Divine spells that are revoked remain in memory but cannot be cast until restored or replaced.   Some casters, like wizards, can store large numbers of spells in external sources such as spellbooks and scrolls. These spells can be memorized later but cannot be cast directly unless a specific class feature or feat allows it.
 

Divine Spellcasting

Many gods offer spell lists that can be accessed in exchange for a small price, such as tribute, behavior, or symbolic alignment. These divine spells do not require a full understanding of the magic behind them. The caster only needs to memorize the correct verbal and somatic components. This makes divine spell lists an accessible and versatile option, especially for those who lack the means or time to study magic in depth.   Divine spells take up memory slots just like any other spell. If a god revokes access, the spell remains memorized but cannot be used until access is restored or the spell is manually forgotten. Casters with access to multiple divine spell lists may choose from any available spell options during a long rest, provided they have the memory space to hold them.   Using a god as a conduit for spellcasting allows them to observe the casters soul allowing them to recognize when one of their rules has been broken. Violating the terms of a god’s spell list or contract will immediately sever your connection to that god, nullifying any access to their spells until reestablished.   Divine contracts can also influence spellcasting by modifying spell cost, casting level, or access conditions. These effects are unique to the god offering them and follow their own set of rules.
 

Casting Stats & Magic Schools

Most spellcasters use a specific casting stat tied to their class to determine the effectiveness of their spells. This stat is used to calculate spell save DCs and attack rolls. If a caster has no assigned casting stat, they instead use the highest stat available that qualifies to cast the spell.   The save DC for a spell is 10 plus the caster’s relevant modifier. Spell attack rolls use a d20 plus the same modifier. These apply to both offensive spells and effects that require the target to resist.   Casters can gain proficiency in specific schools of magic, such as Evocation or Transmutation by using a weapon proficiency slot to specialize in that school. If the caster is proficient in the school of a spell they are casting, they add their proficiency bonus to their casting modifier.   For true casters, this also increases their spell save DC formula for that school from 8 + modifier + proficiency to 10 + modifier + proficiency.