How can a caster optimize to be as least reliant on their caster stat as possible?

[soldersbushwack]

Casters aren't as reliant on their mental casting ability score (call it MEN) as martials are on Str or Dex but a lot of times it is flat out superior to jack up your score to 20 than to waste your ASIs on feats which IMO is a flaw in 5th edition. How can a caster optimize to be as least reliant on their caster stat as possible?

I think MEN is most used for preparing a large number of spells, for MEN to-hit on spells, for MEN to damage on spells, and MEN for saving DC.

Sorcerers and Warlocks don't use MEN for preparing more spells but they can't prepare any more spells at all.

Fullcasters give LEVEL + MEN prepared spells.
Half-casters give LEVEL/2 + MEN prepared spells.

Therefore if you intersperse your levels equally between two fullcasting classes with the same casting attribute A, B you will have A + B + 2MEN prepared spells.

Clerics and Druids (Circle of the Land) gain additional prepared domain or circle spells.

So, some kind of Cleric + Druid multiclass might be best. Going full even stevens is probably suboptimal though.

You'd want to use utility, buff and control spells (which don't have saving throws) such as Wall of Stone. Unfortunately, Cleric and Druid spell lists don't have as many control spells as Wizards do.

[thebiglost1]

Most casters need to Max their caster stat because of both to hit rolls and saving DCs. Only ones I could think that could get away with less than max caster stats would be a true life cleric, paladin or EK/AT that uses their spell slots for heals and buffs.

Beyond those, I'm not sure I would want to play one that didn't.

[CantigThimble]

A bladelock could get by completely fine without a good charisma for a long time.

Armor of Agathys, Hex, Invisibility, Mirror Image, Misty Step, Counterspell and Fly are all great regardless of charisma. In the long term you'll miss lifedrinker and fall behind other melee classes significantly but you will have some pretty sweet utility to make up for that somewhat. I would totally play this character.

[Gtdead]

You can certainly use the domain spells feature of cleric, druid and paladin and storm sorceror. You can also go lvl 3 tome lock or take ritual caster.

Just remember that any kind of multiclass requires you to have at least a 13 in the MEN stat of both your class and the target class. You can't just dumb it.

Also all domain type spell lists go up to spell level 5. To get the strongest spells in these lists, you need to be class level 9.
I think you need to give some more info on the type of build you have in mind. What does this character do except being a glorified wand? Cause I think a warlock or a lore bard will offer about the same flexibility and you can leave charisma at a comfortable 14~ or even lower if you wish. You will save some attributes due to not having to multiclass.

[bid]

Sorcerers and Warlocks don't use MEN for preparing more spells but they can't prepare any more spells at all.
Cleric, druid, paladin, wizard are the only classes that prepare spells. The other classes don't get a stat bonus. Sorcerer/warlock get a flat +1 while bards get a +3.

This trick is very limited:
- only cleric/druid share Wis,
- knowing a single high-level spell is better than having 2-3 lower ones,
- being 2-3 points behind on your DC is bad (as thebiglost1 pointed out), limiting usefulness of dipping paladin/wizard even if you rolled high enough stats.

So yes, you could be a Wis20 cleric, dip druid 1 and prepare 5 level 1 spells in addition to your cleric ones. Is it worth being 1 level behind for your high-level spells?

I'm pretty sure ritual caster (wizard) is better than a dip there.

[PeteNutButter]

I'm sure most know this, but to clarify, Eldritch Knights and Arcane Tricksters have no requirement to MC based on their stat. EK's especially can take an 8 int and just use shield/absorb elements.

It's generally not optimal for MC since the other subclasses offer better fruits. There are also better ways to pick up shield spell, but there could be a few instances where its viable. Maybe a 17th lvl cleric or druid who already took 2 fighter lvls for action surge?

[MaxWilson]

Most casters need to Max their caster stat because of both to hit rolls and saving DCs. Only ones I could think that could get away with less than max caster stats would be a true life cleric, paladin or EK/AT that uses their spell slots for heals and buffs.

Beyond those, I'm not sure I would want to play one that didn't.

Well, Moon Druids of course can get away with a Wis 12ish indefinitely. I would generally recommend feats over ASIs for a Moon Druid. The druid can stick to spells like Conjure Animals, Spike Growth, Goodberry, Polymorph (friendly creature), Enhance Ability, Pass Without Trace, Greater Restoration, Cure Wounds, etc. Boosting your Wis to 20 would open up some options (more effective Faerie Fire, Contagion, Call Lightning, offensive Polymorph) but not IMO enough to justify blowing all of your ASIs on Wisdom instead of Mobile/Sentinel/Resilient (Con)/Lucky/etc.

Necromancers can also get away with a low Int if necessary. Wizards in general don't really need Int to cast iconic spells like Wall of Force, Conjure Elemental, Magic Missile, Shapechange, Teleport, or Haste. Int definitely helps (better Fireballs, Blindness, Bigby's Hand, etc.) but if I had a reason to want to play a low-Int wizard I could have a good time with Int 7.

[DiceDiceBaby]

Well, I was toying with the idea of a Tempest Cleric who was a dedicated close combat fighter and had wisdom as his second lowest stat, for a simple reason: I want as few spells as possible. Sometimes I feel that the number of spells one has access to when they max out their WIS is far too much (especially considering that you can't cast all of them in one day). So the idea of a melee cleric with a few utility spells appeals to me, even if it is "suboptimal" from a caster perspective.

The solution, therefore: don't think like a caster. :)

[Giant2005]

Therefore if you intersperse your levels equally between two fullcasting classes with the same casting attribute A, B you will have A + B + 2MEN prepared spells.

I'd just like to point out that you don't need to intersperse your levels equally for that equation to be true. Just a single level dip in another full casting class (or two levels in a half-casting class) will give you that same equation.

[Talamare]

Basically by focusing on buff spells

Paladin wouldn't even need CHA if it wasn't for his Lv6 ability

[ravenkith]

Here is your answer:

Barbarian 1-3/Druid of the moon X.

You can use your spells in one of two ways:

Buff then, wild shape into combat form -OR- Wild shape into combat form and rage, then use spells out of combat for heals/etc.

Boom. Optimized to not need a high casting stat.

Note that you get unarmored defense CON+DEX + 10, which can be selected in place of the animal's natural armor calculation if it's better, advantage on str rolls (like, say grapples), and a +2 to damage, as well as resistance to mundane melee attacks (at level 1), or resistance to every kind of damage except psychic (at level 3).

Going Paladin (Vengeance?) 2 (or just adding it) could allow you to use your spell slots to smite as desired while getting advantage on all your attacks: nothing there involves using a casting stat, and can yield delicious nova goodness, at the cost of high level abilities.

Note: None of my games (played or run) has ever gone past 15th level, so in all fairness, I tend not to care about capstone abilities etc, as I will NEVER see them.