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[PFKM] Do spellcasters need spell penetration?

Xamenos

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Pathfinder: Wrath
Your analysis is fine, Trashos, but as before it is incomplete.

A: To-hit: You have assumed a naked, unbuffed Octavia. While an interesting mental image, it is not a reasonable assumption to make. Cat's Grace (or Belt +4 but I don't remember what kind of belt you have access to at that point), Haste and Heroism give her a total of +5 AB, and are all buffs she can cast herself. With just another +1 she has a 95% chance to hit, just like panda said. The source of that final +1 is trivial, and left as an exercise for the reader.

B: SR: Math checks out, though I will not examine the case of just Spell Penetration without Greater.

C: Combining the above: I do not disagree with panda, but I will do it because it will be useful to what comes next
No SP: 0.95*0.4=0.38 or 38%
GSP: 0.95*0.6=0.57 or 57%
Just as expected, and mirroring panda's results, with GSP we see a 50% increase on the spells that land compared to without. But, that number is not the number we actually care about. It is only useful as a proxy for

D is for Damage

An L12 Octavia has three choices of Rays to use: Scorching Ray, Hellfire Ray and Disintegrate. For a proper conclusion, we have to examine each. I am assuming no bonuses to damage and I don't remember how reasonable an assumption that is.

Scorching Ray: Each ray deals 4d6+6d6 fire damage, reduced by the Astradaemon's Fire Resistance 10. This gives us an average of 25 damage per ray, 3 rays per round. We could go deeper into examining the full distribution, but it is more effort than I'm willing to expend on this. The average will have to serve for our purposes. Her true Damage per Round is going to be 25*0.38*3=28.5 or 25*0.57*3=42.75. Spell Penetration increases her damage by exactly 50%, which is exactly what we would expect.

Now, the Astradaemon has 213 hit points. Octavia needs to land 9 rays, on average, to kill him. Without SP this means firing 9/0.38, or 23.7 rays, or 8 spells. With SP, this means 9/0.57, or 15.8 rays, or 6 spells.

Hellfire Ray: Each ray deals 12d6+6d6-10 damage. The average is 53. This is barely better than 2 Scorching Rays, 2/3 of a casting, so I am not going to examine this case further. Scorching Ray is a strictly better use of her slots and actions in this fight.

Disintegrate: 24d6+6d6, for an average of 105. No resistance applies, but it is subject to a fort save. A successful save reduces the damage to 5d6+6d6, or 38,5. Octavia should have a DC of 10+6 Spell Level+7 INT+1 Focus, or 24. The Astradaemon has a fort save of 12. Taking this into consideration, the average is 105*0.55+38.5*0.45=75.08. 28.53 without SP, 42.8 with. Marginally better than Scorching Ray.

Octavia needs 3 rays to kill him, so she has to cast 8 spells without SP, or 6 with it. We got the same result as with Scorching Ray, so we can use the spells interchangeably in this fight. This is somewhat fortunate, as Octavia cannot cast 6 Disintegrates at L12. The cause of us being able to use them interchangeably is a spell's nature as a distinct packet of damage. Disintegrate is simply slightly more overkill on average. And this is the same cause of us seeing less than the expected 50% improvement. In both cases we were close to needing 5 spells with SP, with Disintegrate requiring a little less luck than Scorching Ray to get there.

Conclusion? I have none. Spell Penetration improves Octavia's damage against foes with Spell Resistance. This was blindingly obvious to everyone, and so my theorycrafting, like most theorycrafting, was a waste of time. And I am still unsatisfied with it. I ignored the distribution, which would allow us to measure exactly how lucky you need to be to finish him off with less spells than average (the variance of our distribution), and how this number changes with and without SP and for the different spells. I ignored possible sources of increased damage, like a Rod of Empower. I ignored completely the contributions of the rest of the party, which is never a wise thing to do in a party-based game. And I possibly ignored other things that would affect the outcome and I cannot think of at the moment.

If you want to theorycraft properly, you cannot ignore variables like those. You need to take everything into account, or the numbers you arrive to, and use to derive your conclusions from, diverge more and more from reality. There are few things worse than assuming your spherical cows behave exactly like the real ones.

But, I hear you say, you cannot expect us to take every single variable into account. It's too much effort, requires too much time, and there's still the risk of missing something and coming to the wrong result. I hear ya. And, well, I agree completely. Scientists who are extremely well paid to do this for a living still struggle with it. We cannot expect a rando on a forum to do it for a game, of all things. And this is the reason Desiderius's (and Pink Eye's) experimental approach, and the conclusions derived from it, is vastly superior to theorycrafting.

As a +4 bonus in a D20 game would suggest, it increases your probability to overcome SR by 20% in a singular instance. The arithmetic is pretty simple, and positive. You go from a 1/3 chance to a 1/2 chance. Too bad all the significant considerations are rational, rather than mathematical.
You fail statistics forever. Please repeat the class if you have taken it. Or ask Trashos to explain. He, at least, understands why this is wrong.
 

Desiderius

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Insert Title Here Pathfinder: Wrath
Vitals? Maximize? Empower? Elemental Feats/Items? 24DC?

Has anyone here ever actually played a caster?
 

Xamenos

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Vitals? Maximize? Empower? Elemental Feats/Items? 24DC?

Has anyone here ever actually played a caster?
Well, I did say I intentionally ignored sources of additional damage, among other things. Let this be yet another warning on the dangers of theorycrafting.
 

Desiderius

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Insert Title Here Pathfinder: Wrath
But you’re just encouraging Trash by leaving out the basics. Six spells! Might as well just ploink him with Harrim’s Xbow.
 

Xamenos

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Thankfully, we have you to set the record straight lest he assume my spherical cow is any better than his spherical cow.
 

bec de corbin

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Maximize spell is hilarious. Maximize rods are a huge boost to any offensive spellcaster and you can buy a bunch of them if you want, iirc
 

Desiderius

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Insert Title Here Pathfinder: Wrath
Tristian has a robe (Leviathan’s Gift) which gives six per rest.
 

Trashos

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For the time being: I think we are already using the DEX belt. Not sure, because the DEX bonus was given to me by LannTheStupid, but that's my understanding anyway.
 
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1D20 + Caster Level (13) vs SR (27). Player needs to at least match the value.

Setup an inequality where; 0<X<21

X + 13 = 27
- 13 -13
X = 14

Rolling at 14 or greater with 1D20 has a probability of 35%
Adding Greater Spell Penetration adds +4 your caster level for overcoming SR.

X + 13 + 4 = 27
X + 17 = 27
X - 17 -17
X = 10

Rolling at 10 or greater with 1D20 has a probability of 55%.
You're asserting that the comparison should be .55 / .35, yielding a 57% (1.57) improvement to overcome SR. Fine, I get it. My statement of success going from ~1/3 to ~1/2 didn't change. That's what ultimately matters. The conclusion remains the same too.

If you're a full arcane or the sole caster of your party, then Spell Penetration is worth it. Your action economy is dependent on spells. Otherwise, it is not worth it--especially if you're an elf. The opportunity costs to other feats is too significant and the alternatives are numerous.
 
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Maximize spell is hilarious. Maximize rods are a huge boost to any offensive spellcaster and you can buy a bunch of them if you want, iirc

Tristian has a robe (Leviathan’s Gift) which gives six per rest.

My level 14 caster I posted on page 1 has a rod that gives her 5 maximized casts per rest (+3 evoc dc too and makes everything fire for elemental focus) and then my level 14 Eccles has a rod that gives her 3 maximized+empowered casts a rest and ignores spell resistance (and an amulet that raises the dice of CL dependent fire spells by 4). There is so much oomph here for level 14.

The itemization for casters is really fun, imo. I went from daydreaming about Lion’s Claw to looking forward to how I’m going to use my nova caster turns each rest. There are encounters where the martials still have much more favorable circumstances but frankly I enjoy having that texture to the game and not playing a take on all comers style.
 

Trashos

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Lann, we have assumed +4 for DEX bonus. Have we taken a DEX belt into account for that? Or, in other words, you have 3 ability points to spend until lvl12. Where do you want them, INT or DEX?
 

Desiderius

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You're asserting that the comparison should be .55 / .35, yielding a 57% (1.57) improvement to overcome SR. Fine, I get it. My statement of success going from ~1/3 to ~1/2 didn't change. That's what ultimately matters. The conclusion remains the same too.

If you're a full arcane or the sole caster of your party, then Spell Penetration is worth it. Your action economy is dependent on spells. Otherwise, it is not worth it--especially if you're an elf. The opportunity costs to other feats is too significant and the alternatives are numerous.

I’m asserting it because it’s true. 57% is bigger than 20%. Take da feats, nuke some shit.
 

Desiderius

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Insert Title Here Pathfinder: Wrath
Lann, we have assumed +4 for DEX bonus. Have we taken a DEX belt into account for that? Or, in other words, you have 3 ability points to spend until lvl12. Where do you want them, INT or DEX?

You round her off to 18 because the Trans bonus stupidly doesn’t stack then you give her the +4 gloves or belt. She might have the +6 gloves depending how much she uses weapons. Everything else to INT.
 

Xamenos

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For the time being: I think we are already using the DEX belt. Not sure, because the DEX bonus was given to me by LannTheStupid, but that's my understanding anyway.
As I said, this is not a reasonable assumption to make. You should always examine your assumptions when trying to solve a problem like this, or errors start creeping in. Octavia starts with 17 DEX. I assumed she raised it to 18 at L4 or L8, but it could easily have been counting the +1 (enhancement) she gets from her specialization. In that case, Cat's Grace gives only a +1, and we need a further +2 to reach 95% to-hit. It is still a trivial exercise to get it.


1D20 + Caster Level (13) vs SR (27). Player needs to at least match the value.

Setup an inequality where; 0<X<21

X + 13 = 27
- 13 -13
X = 14

Rolling at 14 or greater with 1D20 has a probability of 35%
Adding Greater Spell Penetration adds +4 your caster level for overcoming SR.

X + 13 + 4 = 27
X + 17 = 27
X - 17 -17
X = 10

Rolling at 10 or greater with 1D20 has a probability of 55%.
You're asserting that the comparison should be .55 / .35, yielding a 57% (1.57) improvement to overcome SR. Fine, I get it. My statement of success going from ~1/3 to ~1/2 didn't change. That's what ultimately matters. The conclusion remains the same too.
I am not asserting anything. This is how probabilities work. If you still do not understand why "As a +4 bonus in a D20 game would suggest, it increases your probability to overcome SR by 20% in a singular instance." is wrong, I weep for your teachers. But I will simply say it is possible to arrive at the correct conclusion by coincidence.

Still, double-checking your math lead me to discover an error in Trashos's, panda's and my calculations: 12+13 and 16+9 equal 25. We're 2 short of his SR of 27. The real chances to overcome the Astradaemon's spell resistance are 30% and 50%, and all calculations using the old numbers are wrong. It is embarrassing that none of us noticed.
 

Trashos

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As I said, this is not a reasonable assumption to make. You should always examine your assumptions when trying to solve a problem like this, or errors start creeping in. Octavia starts with 17 DEX. I assumed she raised it to 18 at L4 or L8, but it could easily have been counting the +1 (enhancement) she gets from her specialization. In that case, Cat's Grace gives only a +1, and we need a further +2 to reach 95% to-hit. It is still a trivial exercise to get it.

I cannot make this decision for you, you have to let me know. By taking a DEX, you are going to be missing an INT, and you are going to be missing it by the endgame too. (the base game does not reach lvl20 without cheats or non-full parties).
 
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Xamenos I corrected myself simply enough. That's called poise. You're obviously unfamiliar. Gnash your teeth and spit bile unprovoked. It amounts to nothing other than displaying your failure of character. Even with all of your grandstanding, you're still too cowardly to make a value judgement on the usefulness of a feat, leaving your contributions to this thread insignificant. My career requires me to save academics from themselves routinely, so let me explain things in a way even an insolent coward can understand.

The rate of improvement is a distraction to the point of irrelevance. The difference in result is still only 20%. This is marginal given the alternatives to overcoming or bypassing SR, and the infrequency of enemies with substantial SR that pose a threat to the party. If the character is a full caster, or sole caster of the party, spell penetration feats are worth it by virtue of action economy and poor feat alternatives. Otherwise, the opportunity cost is excessive.
 
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For the time being: I think we are already using the DEX belt. Not sure, because the DEX bonus was given to me by LannTheStupid, but that's my understanding anyway.
As I said, this is not a reasonable assumption to make. You should always examine your assumptions when trying to solve a problem like this, or errors start creeping in. Octavia starts with 17 DEX. I assumed she raised it to 18 at L4 or L8, but it could easily have been counting the +1 (enhancement) she gets from her specialization. In that case, Cat's Grace gives only a +1, and we need a further +2 to reach 95% to-hit. It is still a trivial exercise to get it.


1D20 + Caster Level (13) vs SR (27). Player needs to at least match the value.

Setup an inequality where; 0<X<21

X + 13 = 27
- 13 -13
X = 14

Rolling at 14 or greater with 1D20 has a probability of 35%
Adding Greater Spell Penetration adds +4 your caster level for overcoming SR.

X + 13 + 4 = 27
X + 17 = 27
X - 17 -17
X = 10

Rolling at 10 or greater with 1D20 has a probability of 55%.
You're asserting that the comparison should be .55 / .35, yielding a 57% (1.57) improvement to overcome SR. Fine, I get it. My statement of success going from ~1/3 to ~1/2 didn't change. That's what ultimately matters. The conclusion remains the same too.
I am not asserting anything. This is how probabilities work. If you still do not understand why "As a +4 bonus in a D20 game would suggest, it increases your probability to overcome SR by 20% in a singular instance." is wrong, I weep for your teachers. But I will simply say it is possible to arrive at the correct conclusion by coincidence.

Still, double-checking your math lead me to discover an error in Trashos's, panda's and my calculations: 12+13 and 16+9 equal 25. We're 2 short of his SR of 27. The real chances to overcome the Astradaemon's spell resistance are 30% and 50%, and all calculations using the old numbers are wrong. It is embarrassing that none of us noticed.

I noticed immediately :smug:
 

Trashos

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Mr. Magniloquent, don't sweat it, we are all here to chew gum and insult good people.
I think that the fact that our main numbers are *probabilities* to hit has led to some confusion. When we say that a number X has increased by 20%, by definition that 20% is the 20% of X, not a flat 20%.

Therefore, if you have 40 (be it 40% or 40 potatoes), and it is increased by 20%, the final result is (1+0.2)*40=48 by definition. In the same line of thought, an increase from 40 to 60 (be it percentages or potatoes) is an increase of 50%, because to get the final result you are adding half of your initial value.

Let me know if I have misunderstood something in that discussion. I do not think that this inaccuracy warranted the reactions it got, but you are probably going to have to express yourself more accurately to not be misunderstood.
 
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Trashos You didn't misunderstand anything. My wording was improper. I quickly corrected myself without belligerence. Xamenous seized the opportunity to display his rabid impudence. I suspect he was thrown into a rage after failing to grasp the difference between quantitative and qualitative analysis. Such is the internet. Regardless, my position on the value of SP is clearly demonstrated at this point. There is enough information in this thread for people to make their decisions.
 

Trashos

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Still, double-checking your math lead me to discover an error in Trashos's, panda's and my calculations: 12+13 and 16+9 equal 25. We're 2 short of his SR of 27.

Fixed!
 

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