SR as a reduction in caster level

[Wulf Ratbane]

SR is generally balanced, at any given CR, against a caster of the same level/CR.

A creature that is expected to shrug off half of the spells cast at it will have SR = 10+CR.

I think-- talking OOMA-- that CR's less than 11 are rare outliers.

You could find the "right" SR to use by subtracting the caster's level+10 from the SR. If the result is exactly 0, it means the creature is designed to ignore, on average, half of all spells.

If the result is positive, it means the SR exceeds the caster level-- the creature is sliding towards the "very immune" side of the scale.

If the result is negative, it means that caster level is expected to exceed the creature's resistance, and the creature slides towards the "almost 100% affected" side of the scale.

Just remember, because SR revolves around a d20 roll, that the middle of the scale is 50% and each point from there would be (if I reckon right) a 5% difference.

 

[Fifth Element]

3) Do spells reduced below their minimum CL work at all or are they negated? (i.e., a caster level 7 fireball against someone with SR 3 or more)

Don't confuse spell level with caster level. A CL 7 fireball against a SR 3 creature would be resolved as if it were a CL 4 fireball (4d6 damage, eg).

The CL reduction would only apply as it affects the creature in question. I would not affect the initial casting of the spell at all.

 

[Fifth Element]

Then what about spells that don't allow saves?

I suppose they could get a save, where others cannot.

Like I said, this is really a half-formed idea.