Larian Studios Forums Baldur's Gate III Baldur's Gate III - General system question : which ability is linked to a given spell ?

All in the topic
After five runs of the game and a long pen and paper rpg experience (just nothing in the DnD and alike department) , I'm still really unsure of how the system works on its basic.
Today's question : spellcasting.

How does my abilities influence my chances to hit with a damage spell. Say I'm a ranger and I pick the arrow that entangles (can't remember the name) will I shoot it with my DEX ? my WIS ? something else ?

I suspect that they are a direct schooi of magic to ability bijective relationship...but that's the thing ... I suspect and I want to know And no wiki seems to mention anything like that... sooooo heeeelp please

If you consider wizards who can basically learn any spell , knowing in advance the mechanism would be a great help.

It's mostly by class.

Wizards will use Intelligence for all their spell attacks and save DCs.
Warlocks will use Charisma (as will Paladins, Bards, and Sorcerers when they come)
Clerics, Druids, and Rangers use Wisdom
Arcane Tricksters and Eldritch Knights use Intelligence as they are fluff-wise treated as mini-wizards.

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The spell you are speaking of has two elements:

First you have to hit with a Weapon attack which will use either Strength or Dexterity depending on the weapon (Dex for bows). They will then roll against your spell save DC based on your Wisdom because Ranger.

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There are basically two ways aggressive spells operate.

Spell Attacks - the caster rolls an attack as if it were a weapon

Spell Save - the target rolls a Saving Throw determined by the spell (Strength for Ensnaring Strike) vs a DC determined by the caster's casting trait.

Some spells do use a mix... succeed in an attack to hit the target and then the target makes a save to resist some of the effect.

The spell save DC is 8 + Proficiency Bonus + Spellcasting ability score's modifier

A ranger of 1st to 4th level with 16 Dex and 14 Wis will have a bow attack of +5 (+7 if archery fighting style) due Proficiency bonus of +2 and Dex bonus +3. And Save DC of 12 because - 8 +2 (proficiency) +2 (Wisdom modifier)


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So process in this case is:

Cast spell

Make bow attack with +7 (we'll assume Archery style) and try to match the target's Armor Class.

If misses, the spell lingers because it triggers only on the next hit within the minute duration.

If the attack hits, the spell triggers. The target now must make a Strength saving throw to beat the above ranger's save DC of 12.

If the save fails, the target is affected by the spell. If the save succeeds, the spell fizzles.

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With half-casters whose spell-casting stat is usually secondary, I usually suggest spells that are more along the lines of buffs to self (Jump, Expeditious Retreat, Mirror Image, etc) or others since it means you aren't as heavily impacted by the spellcasting stat's level.

Basically

Cast through technique, learning, and practice, and treating the world like a cosmic rube-goldberg device (Wizards, Artificers, Eldritch Knight, Arcane Trickster) - use Intelligence
Cast through awareness of the self and the world around you on a metaphysical level (Clerics, Rangers, Druids.. some Monks) - use Wisdom
Cast through sheer force of will and inner self-image sufficient to alter reality (Paladin, Sorcerer, Bard, Warlock) - use Charisma

So, Poison Spray cast by Wizard uses Intelligence. Cast by druid uses Wisdom. Cast by Warlock uses Charisma.

If you take the Magic Initiate feat then your casting stat for the associated spells will be based on the named class... so a Wizard with Magic Initiate: Cleric will have a handful of Wisdom-based spells.


Also note that currently wizards being able to cast any spell is probably a bug. Wizards have by far the largest and most diverse spell list of any caster, but there are some spells they generally don't get.

Thank you guys !

Oh, also keep aware of which spells are Concentration. Half-casters get such a small list of spells that you have to be careful curating what spells you take. When we did the tabletop Curse of Strahd game I took 3 total concentration spells on my ranger: Hunter's Mark, Healing Spirit, and Protection from Good and Evil.

If it had been post Tasha's I probably would have taken a Smite spell instead of Hunter's Mark since I played a Strength-based melee Ranger (Defense fighting style)

You can only run one Concentration spell at a time (baring some third party feats we won't see in BG3 because they're Third Party material). So if your cleric casts Bless then you'll want to think carefully before casting Hold Person because that's another Concentration spell and casting it will cause you to drop Bless.

As an side to the good information shared by others here, I'll point out that an exception tends to exist in any situation where you learn spells by virtue of your race; drow and high elf magic traits, for example, grant spells that are controlled by Intelligence, regardless of whether you have another casting class or not - the idea being that you learned these in the wizarding style of academia as part of your upbringing. Another example is Genasi who, if their elemental type grants them a spell or spells, use their constitution as their casting ability for them.

Spells that you get from magic items usually either tell you to use your own casting ability and DC (such items usually require attunement by a spellcaster, so they can do this, knowing that you have a casting class to work with), or they will supply their own attack bonus and save DC as part of the item (for such items that don't require attunement or can be attuned by anyone).

We don't have magic item attunement in the game currently, so formally speaking, all magic items that cast spells should be using a fixed item-set attack bonus and DC.


Currently in game, there are quite a few bugs; there are several spells that use the wrong casting ability, regardless of your class, and several items that are odd in their behaviour related to their spell casting. The advice above, form the other posters is sound and that's what you should follow - where it diverts from that in game, treat it as a bug and report it if you can spare the time.