A Primer on Spell Casting in the new Dungeons & Dragons

The new Basic Dungeons & Dragons PDF is now available, as you probably know. It contains the new procedures for spell casting in D&D, which have a few differences from earlier forms of the game. What hasn’t changed is who can cast spells: Fighters and Thieves can’t, Clerics and Wizards can.

The Basics: Prepared Spells and Slots

Each caster prepares a number of spells at the beginning of the day. The number of spells prepared is equal to their Level plus their Spellcasting Ability Modifier. A caster also has a number of spell slots, determined by their class and level. When a character casts a spell, they expend one slot to power one spell of its level or lower. The list of prepared spells does not change – if you had prepared magic missile, it is still prepared. However, the number of slots you have to cast spells in has been reduced for today.

In addition, if the slot you used was of a higher level than the spell you cast, your spell may have additional effects. For instance, magic missile creates 3 missiles. However, if you were to use a 3rd level slot, it would produce 5 missiles.

The effect of this is to give casters a lot of freedom as to what they do: their spell selection can be quite wide, but they can choose any of those spells to actually cast – and cast repeatedly – depending on the situation. For players of 3E, clerics and wizards now work a lot like the sorcerers of 3E, but sorcerers who could redo their spells known every day! It is, by a fair margin, the most versatile spell-casting system that D&D has had. (Officially, at least).

Casters also have a number of spells they can use an unlimited times per day – cantrips. These cantrips include a number of combat spells, which scale with the level of the caster. These give casters basic attack forms in combat, even when they don’t want to use their more powerful, higher-level spells. (Their role is similar to the At Will spells of 4E).

Casting in Combat

As I’ve been examining in my articles on Initiative in earlier D&D games, one of the major concerns of previous editions was in containing the power of spell-casting in melee. In the early editions, if a spell-caster was struck when they were casting a spell, the spell was spoilt. In practical terms, if a caster failed an initiative check and was hit, they’d lose the spell. 3E, with its use of a cyclical initiative structure, used Attacks of Opportunity to model this behaviour, with spells being spoilt by the caster taking damage. 4E abandoned the spoiling of spells, but still allowed Opportunity Attacks if a caster started casting a ranged spell next to an opponent.

This is not how Basic D&D handles it. Instead, casters may happily cast spells when adjacent to opponents without taking attacks or having their spells spoilt. There is only one limitation: if you use a spell with a ranged attack roll when next to an opponent, you have Disadvantage on that attack roll, the same as if you were using a bow.

Unlike 3E, there is no concept of ranged attack spells ignoring armour and working against a “touch AC”: you still try to hit their unmodified armour class. However, as you use your proficiency modifier + spell-casting attribute modifier to make the attack, you’ll be as effective with that as a fighter or rogue would be.

Resisting Spell Effects

Offensive spells generally allow either a saving throw to avoid the effect or are attack spells (attack roll vs AC) as mentioned above. For a character or monster to successfully save against a spell, they must roll equal to or higher than the Difficulty Class of the spell, which is equal to 8 + proficiency modifier + attribute modifier. In general, this means that any spell a player is going to be casting will have a DC from between 13 and 19. Unlike 3E, spell level is not consulted in the setting of those target numbers. And unlike 1E and 2E, the DC goes up with your caster level; in AD&D, the higher level the target, the less likely the spell would have full effect, and there was no reference to the caster’s effectiveness at casting the spell.

Saving throws, in theory, could draw on any of the six attributes, but most likely link to Constitution, Wisdom or Dexterity. A character either uses their unmodified ability score modifier, or, if it is one of the two attributes they’re good with, they add their proficiency modifier. This means that at first level, a character will likely have saving throw modifiers of -1 to +6, whilst at twentieth level, the modifiers will be -1 to +11.

When these are compared to the potential DCs, it becomes quite apparent that you’re going to have a lot of trouble resisting effects in anything but your primary ability scores.


Another big change to how spells work is concentration: significant spells with duration effects require you to concentrate on them. Concentration can be broken by you taking damage, although you get a Constitution saving throw to avoid losing Concentration. It is also broken by you being incapacitated or if you die.

You can only concentrate on one thing at a time. You may happily cast other spells, but the moment you cast another concentration spell, the spell you were concentrating on will end. Most of the “buff” spells are concentration spells, as are spells like Hold Person.

What else uses concentration? Spending more time than 1 action casting spells! When you ready a spell, it takes longer than an action, so this rule then applies. There are also spells like Dream, which takes 1 minute to cast.

This is a fascinating rule, and one that will likely take a bit to understand all of its ramifications.


D&D has also gone back to the idea of spells having components: Verbal, Somatic and Material, which will be new to players who only played 4E before, but will be familiar to those who played 1E-3E. Interestingly, most material components can be replaced by using a spell-casting implement (such as a wand or holy symbol), although if the spell lists components that have a cost, you must have those components to cast the spell.

The default is that components are not consumed by the spell, but a few spells will have in the entry that they are.

Spell Acquisition

When casters prepare spells, which ones can they choose? This is a primary difference between clerics and wizards.

Clerics get to prepare any spells on the cleric spell list. If that list grows (such as if you move from the Basic D&D pdf to the Player’s Handbook!) they automatically have access to all cleric spells there. In addition, Clerics automatically prepare some spells based on their Domain.

Wizards, meanwhile, can only prepare spells that are in their spellbook, which will rarely contain every spell on the Wizard spell lists! At first level, they select 6 first level wizard spells to put in their spellbook, and they gain two extra spells (of any level they can cast) for each level they gain. It is also possible for them to find spells in the game and copy them into their spellbook.

Ritual Casting

Wizards and Clerics have the option of casting certain spells as rituals. A ritual spell does not use a spell slot to cast, but it takes 10 minutes longer to cast than normal. Ritual spells are identified by a “ritual” tag in the spell’s description.

Wizards may cast any spell they have in their spellbook as a ritual; they do not need them prepared.

Clerics may only cast spells they have prepared as rituals.

The spells that can be cast as rituals in Basic D&D are Augury, Comprehend Languages, Commune, Detect Magic, Divination, Identify, and Silence.

Well, those are the major highlights of the new system. You should take note of the areas of effect (which are broader than in 4E and less beholden to a grid), and it should also be noted that the effectiveness of the spells seem quite high, which is balanced – to some degree – by spell-casters being able to cast not as many as in 1E-3E.


  1. phaezen

    One of the biggest repercussions of the new concentration rule is limiting how many buff spells you can have running.


  2. David

    It’s worth noting that cleric and wizard spellcasting is mechanically the same except clerics can prepare spells from the whole list of cleric spells whereas wizards only know a few spells that they choose and maintain in their spellbook. They start with 6 known at 1st level and learn 2 more each level.

    The only upside seems to be that wizards can cast rituals from anything in their spellbook, whereas clerics must have the ritual spell prepared.


  3. Sebastien

    Good summary however I believe there is a missing part : the cantrips and the ability to cast them at will. It is not what I call not as many many spells as in 1E-3E 😉
    Especially considering they include a basic damage-causing spell which even becomes more effective with spellcaster levels.

    Liked by 1 person

      • Michael

        Can you suggest a rationale why a cleric knows *every* cleric spell (up to their level) but only a sub-set of the cleric cantrips?

        That (apparent) inconsistency doesn’t really seem to make sense, so I’m considering giving clerics access to to cantrips that they do not (yet) have “fixed in their minds” by either allowing them to prepare the cantrip as if it were a spell, or to cast them at will using a spell slot…

        (The latter approach would be more generous, but arguably fits better with the idea that cantrips really are simple spells that _can_ potentially be permanently fixed in one’s mind.)


  4. kyle

    can someone explain casting a spell to me like I’m an idiot?… but only because I am.

    say I’m casting Burning hands, what do I roll for and what bonuses would I add to the roll? do I need to make a separate roll for spells, like firebolt, that require some level of accuracy to hit the target?


    • MerricB

      G’day, Kyle! It really depends on the spell. With Burning Hands, you roll 3d6 for the damage dealt to each creature it could affect. Then, each of those creatures must make a Dexterity saving throw (the DC depends on the spellcaster; at 1st level it will normally be 13). Each creature that fails its save takes full damage, each creature that succeeds takes half damage.


    • MerricB

      Some spells work like weapons and have attack rolls. Firebolt is one of those. The attack bonus is either given in the creature’s stat block, or calculated if a character in the same way a normal attack bonus is: Proficiency Bonus plus Spellcasting Ability modifier. Which ability you use depends on your class (e.g. Clerics use Wisdom and Wizards use Intelligence). Thus, a 1st level Wizard with a 16 Intelligence (+3 modifier) has a +5 bonus to hit with a Firebolt. (+3 intelligence, +2 proficiency).


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s