How do will saves work?

[SangoProduction]

I mean in reference to magic that affects the physical body. Like telekinesis, for example. There are more. But that's what I'm thinking about at this moment for no particular reason whatsoever.

Or to clarify the intent of the question: How do you fluff it when the veteran fighter just says no to magic.

[Buufreak]

The magic voice in your head tells you to do something you don't want to. You tell it to piss off.

[icefractal]

The magic voice in your head tells you to do something you don't want to. You tell it to piss off.For mental stuff sure, but there's a lot of other things that have Will saves.

I'd say that all creatures have the ability to exert control over a very small domain - their own self. This is why you can't Create Water inside peoples' lungs, for example. So spells with a Will save are attempts to act within that domain that superior willpower (compared to the caster) can shut down.

[SangoProduction]

For mental stuff sure, but there's a lot of other things that have Will saves.

I'd say that all creatures have the ability to exert control over a very small domain - their own self. This is why you can't Create Water inside peoples' lungs, for example. So spells with a Will save are attempts to act within that domain that superior willpower (compared to the caster) can shut down.

Ooo. I like that metaphysical explanation.
Let's see another.
(And again, I'm getting the weird feeling like failing to respond to the other commenter is implicitly saying "your comment is bad and beneath my notice." God I hate that lying voice in my head. But it lies with good intent. It wants me to try and empathize and think about how my (in)actions are being perceived however incorrectly it may interpret them.)

[Powerdork]

Stubborn determination (represented by Wisdom) and discipline (represented by a high base save, like monk or wizard training, or like three times as much fighter or rogue training) come together to help you prevent yourself from making glitterdust so bad it blinds you, eject negative energy (or unwanted positive energy) from your soul, or act normally in spite of magical charms trying to worm their way into your head, or look past what's wrong to see the truth (that there is no phantasmal killer here for your life).

Base saves, to some extent, also represent divine favour, sheer luck that commoners couldn't comprehend, or natural resilience such as that of an intelligent item.

I hope this is at least part of what you're asking.

[Biggus]

For mental stuff sure, but there's a lot of other things that have Will saves.

I'd say that all creatures have the ability to exert control over a very small domain - their own self. This is why you can't Create Water inside peoples' lungs, for example. So spells with a Will save are attempts to act within that domain that superior willpower (compared to the caster) can shut down.

I have a kind of similar idea about it. I think of your power level in magic, ki, psionics etc as being an expression of the strength of your life force, channelled in different ways; likewise the superhuman feats which high-level martial characters can perform. Levelling up represents your life force getting stronger as you grow as a person by overcoming difficult challenges. Any attempt to affect you with magic or psionics is an attempt to interfere with your life force, and saving throws represent your ability to resist that.

[Rynjin]

It takes a lot of effort and a lack of effort on the opponent's part to break through The Manton Limit (https://worm.fandom.com/wiki/Manton_Effect).

[NichG]

I'd say its like the feeling of being sleepy and resisting going to sleep, or the feeling that something you're doing is causing pain but you have to get yourself to do it anyhow, or the feeling when the environment is filled with a lot of noise or distractions and you're trying to concentrate. So basically the metaphysics would be that spells that provoke a will save don't act by directly changing things (that'd be a Fort save or Reflex save), but instead create or mess with perception in a way that the more the person receiving it goes along with it, the more effect it can have. That could be at the level of just paying attention to something and considering what if it were real (illusions), giving into sensations of being sleepy or happy or friendly (various enchantments), etc. For more spiritual things (like Will saves vs positive/negative energy effects), there would presumably be some kind of corresponding sensation that just doesn't exist in the real world that it's piggybacking on, or maybe its just the same kind of sleepiness except a more serious 'slip into a coma / stay awake' kind of thing.

[Jay R]

The wizard is trying to work her will on the world by sheer mental control. OK, fine, she can mentally create fireballs, create walls of stone, etc., and nobody can stop her. But when she's trying to mentally control *me*, there are two minds involved. I can push back along the mental conduit between us that she created.

It's like the difference between being alone and being on a date. When I'm alone, I can watch any movie I want, but when there's two of us, choosing a movie isn't automatic; it gets much more complicated.

Or consider a phone call. I can always get out of it by hanging up. With magic, I can't always hang up, but I can try.

[Chronos]

You're not necessarily pushing back against a mind, or a physical force: You're pushing back against the magic itself. If you're sufficiently strong-willed, the enemy's magic can't intrude on you at all to even attempt to have its normal effect.