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Baldur’s Gate 3 Guide to Spellcasting

In this Baldur’s Gate 3 Guide, I’m going to explain everything you need to know about Spellcasting in BG3. What are Cantrips? How do Spell Slots Work? What is Concentration? How do I Prepare Spells? These are some of the things we’ll cover in this video. If you’ve been struggling with your Spellcaster, or you just need a refresher on how these things work, read on for some helpful information!

Baldur’s Gate 3 Guide to Spellcasting

  • Which Classes can Cast Spells in BG3?
  • What is a Spellcasting Ability Modifier?
  • What is Spell Difficulty Class?
  • What are Spell Slots?
  • Why do some spells not consume Spell Slots?
  • Why can’t I use all my spells?
  • Why did my spell end early?
  • What happens if I Multiclass as a Spellcaster?
  • There are many facets to Spellcasting in BG3, and there’s a lot that goes into how each Spellcaster works, since they are all a little different. However, they do have many things they share in common, and in this BG3 Spellcasting Guide we’ll go through what those things are and just how they work. First, let’s take a look at which Classes can cast Spells in Baldur’s Gate 3.

    Which Classes Can Cast Spells in BG3?

    Many Classes in BG3 can cast Spells, but some can cast more Spells than others and higher level spells as well, so let’s get into which they are.

    Full Casters

    Spellcasters that can reach Level 6 Spells in BG3 are sometimes referred to as “Full Casters”, and there are a total of 6 Classes that can do this. These are:

    You’ll notice that there is an * next to Warlock, and this is for 2 reasons. First, their Spell Slots technically only go up to Level 5, but they can learn one Level 6 Spell at Warlock Level 11. And second, they have far fewer Spell Slots than all other Full Casters, and their Spell Slots operate a bit differently, which I’ll get into later on in this Guide.

    Baldur's Gate 3 Spellcasting Guide Spells

    Half Casters & One-Third Casters

    This means half of BG3’s Classes are “Full Casters”, which is quite a few to say the least. However, there are also Classes that can cast Spells that cannot reach Level 6 Spells and these are:

    Paladins and Rangers are sometimes referred to as “Half Casters” meaning they will gain half the Spell Slots and Level of Spells as that of a “Full Caster”. This means they will only reach Level 3 Spells, instead of Level 6.

    Eldritch Knights and Arcane Tricksters are sometimes referred to as “One-Third Casters” since they will only reach Level 2 Spells, and only gain 1/3 of the Spells that “Full Casters” gain.

    This means a total of 10 Classes of 12 can cast Spells in BG3, which is quite a lot, and all the more reason to become familiar with how Spellcasting works, and just about every party in BG3 will have 1, 2 or even 3 characters that can cast some spells.

    What is a Spellcasting Ability Modifier?

    Each Spellcaster in BG3, whether Full, Half or One-Third, will use one Ability to determine how likely it is to successfully cast their Spells on a hostile target. These Abilities are Charisma, Wisdom or Intelligence, and each Class that cast Spells will use one of these Abilities for this purpose, and they are as follows:

    When casting a hostile spell, all Spellcasters will use the Modifier of their Spellcasting Ability and add that to either the Attack Roll of the spell, or its Spell Difficulty Class, whichever is applicable. So let’s dive into that a bit.

    Baldur's Gate 3 Spellcasting Guide Spellcasting Ability Modifier
    Spellcasting Ability Modifier

    What is Spell Difficulty Class?

    Spells That Make Attack Rolls

    There are generally two different types of hostile spells in BG3 that target enemies specifically. The first, are spells that target their Armour Class (AC), and operate similarly to Weapon Attack Rolls. You can see if this is the case on the tooltip, since these Spells will say “Attack Roll” on them, and there will NOT be an Ability Save listed on them. These spells are ALWAYS damage dealing spells, even though they may have additional effects.

    Baldur's Gate 3 Spellcasting Guide Armour Class
    Armour Class

    In this case the Spellcaster will add their Spellcasting Ability Modifier to their Attack Roll, along with their Proficiency Bonus, which is +2 at the beginning of the game, but will rise to +3 at level 5, and +4 at level 9. The higher their Spellcasting Ability Modifier, the higher total they will have on their Attack Roll.

    If the Spell Attack Roll meets or exceeds the AC of the enemy, the spell will connect and make a Damage Roll based on the damage of the spell. You can see how much damage a spell can deal on its tooltip, and note that your Spellcasting Ability Modifier is not added to your Damage Roll, only your Attack Roll.

    Spell Attack Roll Nuances

    Spells that target the AC of an enemy benefit from a High Ground bonus (+2) if they are Ranged Spells and they are above the enemy. However, they have a High Ground penalty (-2) if they target enemies above them, just like Ranged Weapon Attacks.

    They also suffer Disadvantage if an enemy is within melee range of them, just like Ranged Weapon Attacks, but some Spells like Inflict Wounds or Shocking Grasp target AC, and don’t suffer this penalty because they can only be cast in melee range.

    Additionally, Spells that make Attack Rolls benefit from Advantage, meaning if an enemy has any Status Effect that provides Advantage to attackers, these types of spells will be more likely to connect. Being Hidden is also a great way to gain Advantage, particularly when beginning a combat encounter.

    Spell Difficulty Class (DC)

    The other type of hostile spell in BG3 doesn’t make any Attack Roll at all, and does NOT target AC. Instead these spells target one of the 6 Abilities (STR, DEX, CON, INT, WIS, CHA), and use what is called your Spell Difficulty Class, or Spell DC for short, to determine if they succeed or fail. Many of these types of spells don’t deal any damage at all, and provide some other negative effect, but many deal damage as well.

    A character’s Spell DC is equal to 8 + Spellcasting Ability Modifier + Proficiency Bonus. At level 1, the highest Spell DC you can have is 13, since you can’t have higher than +3 on your Spellcasting Ability Modifier during Character Creation, and your Proficiency Bonus would be +2.

    Baldur's Gate 3 Spellcasting Guide Saving Throw
    Saving Throw

    When you target the Ability of an enemy with a spell, that enemy makes what is called a Saving Throw. They roll the D20 or 20 sided die, and add their Ability Modifier for that Ability to their roll. If your Spell DC is 13, then they need to reach a total of 13 or higher between their roll and their Ability Modifier in order to Save against your spell. If they fail, then whatever the spell does will trigger, and Damage Rolls are made if needed. If they succeed they may take no damage or effect, or take half damage depending on the spell. Make sure to read the spell tooltip, to find out which is the case.

    You can see the Ability Modifiers of enemies in BG3 by pressing “T” and mousing over each Ability. Make sure that you target the lower Abilities of characters with these types of spells, otherwise you will have a very slim chance to succeed. For instance, don’t target an Ogre with a spell that targets STR since they will get a huge bonus to their roll, and will likely “Save” against your spell.

    The Ability Improvement Feat can be used to raise your Spellcasting Ability Modifier further, and is a good Feat for every Spellcaster. If you fling lots of spells, you will definitely want to reach +5 in your Spellcasting Ability Modifier eventually, which is the highest you can go with Ability Improvement in BG3, though equipment can take you higher.

    What are Spell Slots?

    Now that we’ve explained that, lets get into a bit more detail about Spell Slots. What are Spell Slots? Spell Slots are essentially a finite resource that Spellcasters use to cast their spells with. These only replenish on Long Rest, so once you use them all, you cannot cast any more Level 1 or higher Spells until you Long Rest. This means, don’t burn them all in one fight, or be prepared to Long Rest often.

    Spellcasters can only cast spells using a Spell Slot that’s the same level or higher of the spell they are trying to cast. You cannot cast Level 2 Spells with Level 1 Spell Slots for Instance. But you can cast Level 2 Spells with Level 3 Spell Slots.

    Baldur's Gate 3 Spellcasting Guide Spell Slots
    Spell Slots

    Why would you cast a Level 2 Spell with a Level 3 Spell Slot? Well maybe you really need to cast that spell and have no Level 2 Spell Slots left, or maybe the spell will be “Upcast” improving its effect. Many lower level spells in BG3 can be cast using higher level Spell Slots, and a lot of these spells gain more damage (like Burning Hands) when doing so, or allow you to target more enemies with them (like Blindness). Pay attention to the tooltips of each spell, so that you understand which can be Upcast, and which can’t. This will help you make better decisions about which spells to cast with which Spell Slots.

    Warlock Spell Slots

    Warlock Spell Slots operate a bit differently, as I mentioned before, and their Spell Slots will actually increase in Level as they gain Warlock Levels. This allows them to cast any Spells they know with these Spell Slots, and lower level spells, that can be Upcast, are always Upcast when using them.

    However, they only have 2 Spell Slots at level 2, and 3 at level 11, which means they have to be way pickier about the spells they use in combat, since they won’t be able to cast many before they run out of Spell Slots. It is not uncommon for Warlocks to use all their Spell Slots each combat. The upside though, is that Warlock Spell Slots recharge on Short Rest compared to the Long Rest of all other Spellcasters, so they can gain them back in between combats much more easily.

    Baldur's Gate 3 Spellcasting Guide Warlock - Scorching Ray
    Warlock spell – Scorching Ray

    Why do Some Spells Not Consume Spell Slots?

    Not all Spells in BG3 consume Spell Slots though, and that is usually because they are either a Cantrip or a Ritual Spell. However, sometimes certain Races, Classes or Equipment will let you cast a spell once per day without using a Spell Slot. But what are Cantrips and Ritual Spells?

    Cantrips are essentially Level 0 spells that can be cast an infinite number of times outside of combat, and once per turn inside of combat, that consume no Spell Slots. These are generally less powerful spells, like Fire Bolt that sort of operate as a “basic attack” for Spellcasters. However, some can also provide other effects, like Guidance, which adds 1-4 to your Dialogue or Skill Checks, which makes you much more likely to succeed in these.

    Baldur's Gate 3 Spellcasting Guide Cantrip Eldritch Blast
    Cantrip Eldritch Blast

    Ritual Spells are spells that can be used outside of combat without consuming a Spell Slot, but will consume Spell Slots if used in combat. These are very specific spells, and there are not many of them in the game, but you can recognize them by the Ritual Icon and the word Ritual next to Action. You can select many of these with the Ritual Caster Feat.

    Why Can’t I use My Spells in Combat?

    Sometimes players can’t use their spells in combat and they wonder why. Either they are greyed out, or they cannot find them on their Action Bar, but either way they can’t seem to use them in combat. Well there are reasons for that.

    If a Spell is greyed out make sure you have Spell Slots of the right level

    First, do you have enough Spell Slots of the right level or higher remaining? If not, these Spells will appear greyed out on your bar and you won’t be able to cast them until you Long Rest (or Short Rest if you’re a Warlock).

    Second, have you expanded your Action Bar so that you can see all of your spells? Many players don’t even know they can do this, and it hides a lot of spells and other Actions from the player when they don’t. Make sure you do this, and setup your Action Bar properly.

    Lastly, did you Prepare the spell you are trying to cast beforehand? Many Spellcasters in BG3 know a lot of spells, but cannot cast them unless they are Prepared. The following Classes must Prepare their spells before they can cast them:

    The advantage of these Classes is that they know far more spells than Classes that don’t need to Prepare them, but they must Prepare them in order to cast them. This means if you walk into combat and want to cast Fireball with Wizard, but forgot to Prepare it beforehand, you won’t be able to.

    Prepare Spells

    To Prepare spells, hit the “K” key and click on any already Prepared spell to remove it from your Prepared spells, and click any non-Prepared spell to add it. You will be able to Prepare one spell for each level of these Classes taken, plus your Spellcasting Ability Modifier. So if you were level 4 and had 16 Charisma on your Paladin, you would be able to prepare 7 Spells. If you were level 10 and had an INT Modifier of +4 on your Wizard you could Prepare 14 spells.

    Why Did My Spell End Early?

    Many spells in BG3 require Concentration in order to maintain the effect of the spell. For instance, if you cast Cloud of Daggers, you will “Concentrate” on that spell, and it will remain as an AoE on the battlefield as long as you maintain your Concentration on it.

    You can only “Concentrate” on one spell at a time in BG3, so if the next spell you cast also requires Concentration you will end your Concentration on Cloud of Daggers, effectively dismissing it from the field, and begin Concentrating on the new spell.

    Baldur's Gate 3 Spellcasting Guide Cloud of Daggers
    Cloud of Daggers

    But this doesn’t only happen in combat. For instance, if you use Enhance Ability on someone for a Dialogue Check, you will Concentrate on that spell. However, if another Dialogue comes up and you cast Guidance to improve their chances, you will end your Concentration on Enhance Ability and begin Concentrating on Guidance instead, ending the effects of Enhance Ability, because both require Concentration. Try to plan accordingly and don’t waste spells by overriding them with others before you mean to.

    Concentration can end another way however, and that is by taking damage. When a character takes damage while Concentrating on a spell in combat, such as on Bless or Cloud of Daggers, they must make a Concentration Saving Throw using their Constitution Modifier. If they fail, the spell ends. If they pass, the spell continues. This repeats for each source of damage the character takes.

    This makes Proficiency in Constitution Saving Throws phenomenal for Spellcasters, since this further adds your Proficiency Bonus to these rolls. Sorcerers have this by default, as do Fighters and Barbarians, but you can also gain this Proficiency with the Resilient Feat. Note that the Warcaster Feat provides you Advantage when making Concentration Saving Throws, allowing you to roll twice and use the higher of the two rolls, which is excellent for Spellcasters who use a lot of spells that require Concentration.

    And one last tip, you can end your Concentration early if you want by clicking the “X” icon under your portrait. This lets you end hostile AoEs after a battle is nearly won, or is already over, so that your party members don’t accidently walk into them.

    What Happens When I Multiclass a Spellcaster?

    If you’re interested in what happens when you Multiclass, I highly suggest you check out our Multiclassing video for all this information, since we have an entire video dedicated just to that!

    Stay tuned for more Baldur’s Gate 3 content as we update the other Builds, and be sure to drop by our Twitch Channel if you have questions about the game. If you need something specific, check out our Baldur’s Gate 3 Wiki which is being worked on night and day, as well as our Baldur’s Gate 3 Guides.

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