Spell Sniper Vs. +1 to Ability Modifier

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#1

Yunru

Sep 03, 2014 5:39:21

Note: The following calculations ignore (dis)advanatge. Also, maths. You have been warned.

Note #2: This might also be able to be used for working out Sharpshooter, although I daren't claim as such.

Note #3: It is also assumed that you only add 1 +stat mod, if any, and that it's the same stat used to cast with.

 

I already posted part of this in the Warlock guide, relating to Eldritch Blast with a Cha modifer. I've since streamlined the maths, cut out the calculations and accounted for No Cover and not adding a +stat mod to the damage.

 

Now onto the maths:

I'll be using (slightly) different notation for including a +stat mod and not, due to having done said calculations at different times.

 

With +Stat Mod, here's the difference that taking a +1 to a stat mod compared to the Spell Sniper feat works:

With no cover, the difference in average damage is: (100Y+5(AdB)+5X+5)/100

with partial cover, the difference in average damage is: -(100Y+5(AdB)+5X+5)/100

with 3/4 cover, the difference in average damage is: -(100Y+20(AdB)+20X+20)/100

 

Here Y is the chance of hitting as a decimal, X is your Stat Mod and AdB is the average of the damage dice rolled (both X and Y are the number *before* you take an ability bump/spell sniper).

 

With no +Stat Mod, here's the difference that taking a +1 to a stat mod compared to the Spell Sniper feat works:

With no cover, the difference in average damage is: C/20

with partial cover, the difference in average damage is: -C/20

with 3/4 cover, the difference in average damage is: -5C/20

 

Here there's only one variable, C, which is the average damage the spell would do on a (non-critical) hit.

 

 

Discuss, nitpick, etc.

#2

Yunru

Sep 04, 2014 17:18:25

Dammit! I knew I shouldn't of warned of maths!

In other news, updated it to reflect X and Y being pre-abi/spell sniper (it always was, just never stated).

#3

Novacat

Sep 04, 2014 20:51:10

Maybe supplement your numbers with an explanation of what's going on. I see a wall of math, and have no idea how I'm supposed to parse it.

 

Give us a couple of conclusions we can draw from the numbers to make them meaningful.

#4

Dyndrilliac

Sep 05, 2014 18:50:24

The average character gets 5 ability score improvements, so if they start off with their primary casting stat at 16 then they can max it out and still have 3 feat choices. Why treat it as a choice between Spell Sniper and +1 to Casting Ability?

#5

Yunru

Sep 06, 2014 0:16:59

Because then you know which you want to take first. Or you might be multiclassing and thus get less.