Spell Resistance (feat chain)

[rferries]

Three guesses as to what these feats give you. There's debate about how useful SR is, so the numbers below could be bumped up or down, depending (or even consolidated into one feat). All the feats after the first are particularly helpful for monsters and monster PCs with some pre-existing amount of SR.

Spell Resistance [General]
Through special training, prior magical exposure, or sheer force of will, you have gained some measure of resistance to spells.

Benefit
You gain spell resistance equal to your character level +5.

Special
A fighter may select Spell Resistance as one of his fighter bonus feats.

Improved Spell Resistance [General]
Prerequisites
Spell Resistance or innate spell resistance

Benefit
Your spell resistance increases to your character level +10.

Special
A fighter may select Improved Spell Resistance as one of his fighter bonus feats.

Greater Spell Resistance
Prerequisites
Improved Spell Resistance, Spell Resistance or innate spell resistance

Benefit
Your spell resistance increases to your character level +15.

Special
A fighter may select Greater Spell Resistance as one of his fighter bonus feats.

Adaptive Spell Resistance
Prerequisites
Spell Resistance or innate spell resistance

Benefit
Your spell resistance automatically lowers when you are the target of beneficial spells, with no action required on your part. You may choose not to lower it if you so wish.

Special
A fighter may select Adaptive Spell Resistance as one of his fighter bonus feats.

EDIT: Since there's still healthy debate over the utility of spell resistance, here's some higher-powered feats.

Spell Resistance [General]
Through special training, prior magical exposure, or sheer force of will, you have gained some measure of resistance to spells.

Benefit
You gain spell resistance equal to your character level +5. At 6th level this improves to your character level +10. At 12th level this improves further to your character level +15.

Special
A fighter may select Spell Resistance as one of his fighter bonus feats.

Alternatively (more powerful but less conventional scaling):

Spell Resistance [General]
Through special training, prior magical exposure, or sheer force of will, you have gained some measure of resistance to spells.

Benefit
You gain spell resistance equal to twice your character level.

Special
A fighter may select Spell Resistance as one of his fighter bonus feats.

And finally:

Adaptive Spell Resistance
Prerequisites
Spell Resistance or innate spell resistance

Benefit
Your spell resistance automatically lowers when you are the target of beneficial spells, with no action required on your part. You may choose not to lower it if you so wish.

Additionally, your spell resistance applies against spells that do not allow spell resistance. You must be targeted by the spell (including ranged and melee touch attacks) or in the spell's area of effect (including cloudkill effects and the like) to be allowed a check, and do so with a -5 penalty to your effective spell resistance. This feat may or may not apply to other types of spells, at the DM's discretion.

Special
A fighter may select Adaptive Spell Resistance as one of his fighter bonus feats.

[Deepbluediver]

4 Feats seems kind of expensive, even if this is mechanically attractive (if only because of how powerful spellcasting is).

[Beneath]

It is expensive, but on the other hand those four feats give you a 75% chance of resisting any SR-allowing hostile spell people throw at you, and let you ignore the rule that SR applies to beneficial spells even if your DM is strict with it (I have never known one who was).

That's pretty solid.

There's an epic feat to improve your spell resistance by a mere two points; the feats in this tree improve it by 5 per feat (except Adaptive, which improves it laterally). Arguably the epic feat is underpowered, but I don't think merely pricing this at four feats makes it cost too much for what it does.

[Deepbluediver]

It is expensive, but on the other hand those four feats give you a 75% chance of resisting any SR-allowing hostile spell people throw at you, and let you ignore the rule that SR applies to beneficial spells even if your DM is strict with it (I have never known one who was).

That's pretty solid.

It's often been pointed out, though, that the spells that allow for SR or saves are only a portion of the problem. There are plenty of broken spells that circumvent this entirely; it doesn't stop a Tier-1 class, just makes them think a little harder. If you're having a problem with spellcasters in your games, then 4 feats across multiple levels just to deal with SOME of their broken abilities is way to expensive IMO.

Why not cut it down to one or two feats at most that scale?

[rferries]

It is expensive, but on the other hand those four feats give you a 75% chance of resisting any SR-allowing hostile spell people throw at you, and let you ignore the rule that SR applies to beneficial spells even if your DM is strict with it (I have never known one who was).

That's pretty solid.

There's an epic feat to improve your spell resistance by a mere two points; the feats in this tree improve it by 5 per feat (except Adaptive, which improves it laterally). Arguably the epic feat is underpowered, but I don't think merely pricing this at four feats makes it cost too much for what it does.

It's often been pointed out, though, that the spells that allow for SR or saves are only a portion of the problem. There are plenty of broken spells that circumvent this entirely; it doesn't stop a Tier-1 class, just makes them think a little harder. If you're having a problem with spellcasters in your games, then 4 feats across multiple levels just to deal with SOME of their broken abilities is way to expensive IMO.

Why not cut it down to one or two feats at most that scale?

Thank you both for your feedback! I've included some higher-power feats above.