Dungeons and Dragons: Magic & Spellcasting

The spellcasting ability you use depends on the class you choose. This ability determines how effective your spells are. For example, Bards, who primarily focus on spellcasting, use Charisma as their spellcasting ability. In contrast, classes like Rangers, which have skills beyond spellcasting, use Wisdom as their spellcasting ability, even though their primary class ability might be different. Your spellcasting ability is used for both your spell attack rolls and saving throw DCs.

To calculate your spell attack bonus and spell save DC, refer to the Spellcasting Ability section in your class description.

When a spell requires you to make a spell attack, you roll a d20 and add your spell attack bonus to the roll. This total is compared to the target’s Armor Class to determine if the attack hits.

For spells that require a saving throw, the target must roll a d20 and add the appropriate saving throw modifier (e.g., Wisdom, Dexterity) to try and beat your spell save DC. Your DM may ask you what kind of saving throw the target needs to make. Always refer to the spell description for the specific ability score.

If a spell doesn’t specify an attack roll or saving throw, you generally don’t need to roll anything unless your DM asks for a check in specific circumstances.

Spells are divided into levels, from 1st to 9th, with 0-level spells called Cantrips. Cantrips can be cast an unlimited number of times per day, while other spells require the use of spell slots. Each day, after a long rest, you regain all available spell slots for your level. Spell slots can only be restored by another long rest unless you have a special ability, like a Warlock who regains spell slots after a short rest.

You can cast a spell using a spell slot of its level or higher. Check your class table to see how many spell slots you have.

Spells may require verbal (V), somatic (S), or material (M) components. Verbal components require you to make audible noise, and somatic components involve hand movements. If you have weapons or a shield in hand, you may need to drop them temporarily to perform somatic components.

Material components are specified in the spell description. If you have a spellcasting focus (e.g., holy symbol, staff), you can ignore material components unless they have a listed gold cost. Materials are usually not consumed unless stated otherwise in the spell description.

At the top of a spell description, you’ll find its range, which determines how far away the target can be. Some spells have special ranges like Touch or Self. Touch spells require you to be in contact with the target, and Self spells either target you or originate from you.

Casting Time
Casting time is also listed at the top of a spell description. Most spells have a casting time of one action, meaning they happen immediately and are the main action for that turn in combat. Spells can also have casting times of one bonus action or one reaction, which allows for additional actions in the same turn. Remember, you only get one reaction per round, so use it wisely.

Spells with longer casting times (e.g., 1 minute or more) are generally not useful in combat but can be potent outside of it.

Bonus Action Spells
If you cast a spell with a casting time of one bonus action, you cannot cast another spell during your turn unless it is a Cantrip. Some groups modify this rule, allowing two spells per turn as long as one is 2nd level or lower. Discuss this with your DM to be on the same page.

There are no restrictions on casting reaction spells during your turn.

Ritual Casting

Some classes have the Ritual Casting feature, which allows them to cast certain spells without expending a spell slot. Ritual casting increases the spell’s casting time by 10 minutes. Only spells with the "ritual" tag can be cast this way.

The duration of a spell, found at the top of its description, tells you how long it lasts. Many spells require concentration to maintain their effects. If you take damage while concentrating on a spell, you must make a Constitution saving throw. The DC is either 10 or half the damage taken, whichever is higher. Failing this save ends the spell. Concentration is also broken if you cast another concentration spell or if you become incapacitated.

Spells can deal various types of damage, such as acid, bludgeoning, cold, fire, force, lightning, necrotic, piercing, poison, psychic, radiant, slashing, and thunder. Always specify the damage type when reporting the damage you’ve rolled.

Many spells impose conditions on their targets, like being charmed, frightened, or paralyzed. A list of conditions and their effects can be found on page 290 of the Player’s Handbook. Check the spell description to understand the condition it imposes.

Some spells affect an area rather than a single target. These areas can be spheres, cones, cubes, cylinders, or lines. While these shapes are usually well-defined, cones can sometimes cause confusion. For example, a 30-foot cone extends 30 feet from its origin and is 30 feet wide at its base. You can choose the direction the cone faces.

Most classes learn new spells as they level up. Your class table will show the number of spells known at each level. When this number increases, you can choose new spells, but they must be of a level for which you have spell slots. If you gain spellcasting levels from multiple classes, only the levels in the class you’re learning from determine the spell levels available.

Some classes prepare spells each day. The number of spells you can prepare is listed under Preparing Spells in your class description. Although you can theoretically prepare a new set of spells each day, most players stick to a favorite set, swapping out a few based on the challenges ahead.

If it’s not the right moment to cast a spell, you can "ready" it by declaring a trigger and the spell you intend to cast. For example, "Once the ghost reappears, I will cast Guiding Bolt," or "If they shove me off the cliff, I will cast Fly on myself."

Readying a spell requires concentration, which can interfere with other concentration spells. The spell slot is used even if the trigger doesn’t occur, or you lose concentration before the spell is cast.

Illusions and enchantments can be complex to adjudicate. Illusions can deceive creatures unless they have reason to disbelieve them. Common spells include Minor Illusion, Silent Image, and Major Image. The effectiveness of illusions often depends on the creature's perception and special senses.

Enchantments, like charm spells, affect a creature’s mind without altering its personality. Familiarize yourself with the charmed condition (page 290 PHB) and understand the hierarchy of enchantment spells, such as Friends, Charm Person, Suggestion, and Dominate Person.

Not all spells fit neatly into categories like damage type, condition, area of effect, or saving throws. For these spells, you must carefully read the entire description to understand their effects. If you’re unsure about how a spell works, you can consult resources like @JeremyECrawford on Twitter or D&D subreddits.

When trying to understand a spell, take the text literally. If the description doesn’t say the spell does something, then it doesn’t do that thing. And remember, the only person you need to convince about how a spell works is your DM. Sometimes, even the DM will get it wrong, and that’s okay.