D&D 3E/3.5 Problems with 3.5 Power Attack?


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MadScientist

First Post
I just thought I would show people where that damage calculation comes from. (MS if I made a mistake here let me know) Since I was finally interested enough to derive it for myself.

Average Damage= (% chance hit) * (Ave. Dam. per hit) + (% chance Crit) * (Ave. Dam. per hit) * (Crit Multiplier-1)

Where:
AD is average damage per attack
H is the number needed on a d20 to hit (maximum 20, minimum 2)
D is the average damage per non-critical hit
R is the critical threat range
M is the critical damage multiplier

AD = [(21-H)/20]*D + (R/20)*[(21-H)/20]*D*(M-1)
AD = D*(21-H)/20 + [D*(21-H)/20]*(R*(m-1)/20)
AD = D*(21-H)/20*(1 + R*(m-1)/20)

The the case of the Ogre we have:
AD = (16)*[21-(10)]*(1 + (1)*[(2)-1]/20)
AD = 8.8 * 1.05 = 9.24 Exactly as Mike Sullivan predicted (I'm sure he is not surprised ;-p).

I believe the one flaw with this equation is if (21-H) < R then average damage will be slightly inflated, because you can not deal extra crit damage if you do not actually hit. This can be alleviated by replacing R with (21-h) in those rare occasions. (If this flaw doesn't actually exist could some one tell me why.)
 

Staffan

Legend
Re: Still a bit OT

Winternight said:

Thanx
If I undderstood that correctly a 19/x2 weapon would be 1.1 because you are having a crit in 10% of all hits.
22x damage in 20 hits -> 1.1
Also would be a 20/x3 weapon 1.1 because you hit in 1/20 a critical but then you do 3 times damage.
22x damage in 20 hits.
Correct. As pointed out later in the thread, there are corner cases where the things you're attacking are so hard to hit that some rolls that would ordinarily be threats will be misses instead (if you use a longsword but is fighting something you can only hit on a 20, it's essentially the same as a 20/x2 weapon), but basically that's correct. The wasted threat range will probably not be much of an issue with a plain longsword, but it might come into play with a rapier or scimitar - especially if you use the 3.0 rules where keen and improved critical stack to give you a threat range of 12-20.
 

Winternight

First Post
MadScientist said:
Average Damage= (% chance hit) * (Ave. Dam. per hit) + (% chance Crit) * (Ave. Dam. per hit) * (Crit Multiplier-1)
You can simplyfy that. And then you have exact the same formula as Mike.
(% chance hit) = h
Ave. Dam. per hit = d
chance Crit = c
Crit Multiplier-1 = m
c = h*(tr) (tr = threat range : 20~1/20, 19-20 ~2/20, ...)

Average Damage= h*d+h*tr*d*m
= h*d*(1+tr*m)

and then you have the same equation as in your last line.
 
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Winternight

First Post
I believe the one flaw with this equation is if (21-H) < R then average damage will be slightly inflated, because you can not deal extra crit damage if you do not actually hit. This can be alleviated by replacing R with (21-h) in those rare occasions. (If this flaw doesn't actually exist could some one tell me why.)
As i understand teh formula (and as Staffan helped me), it doesn't matter. Because you can also thro a D20 after you have hit.

Player: I hit AC xx
DM : roll to see if you score a critical
player: Damm one under the Threat range.


Also as seen in you first line: the chance of a criticak is linked to the chance to hit. % chance Crit = % hit*Threat range.
I you don't hit you don't score a critical

You can also look into my small exel sheet.

look into my next post sorry
 
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Cyraneth

First Post
How would all of this look if Power Attack provided 1.5 times the penalty as a bonus to damage? I mean, let it work like the Strength bonus.

I know that would make most take an even penalty (-2, -4, -6, etc.) to get the most out of the feat, but don't people try to get an even Strength bonus when using a two-handed weapon too?

- Cyraneth
 

Staffan

Legend
Cyraneth said:
How would all of this look if Power Attack provided 1.5 times the penalty as a bonus to damage? I mean, let it work like the Strength bonus.
I think Andy Collins mentioned on his boards that they considered that, but decided that it would be too much math while actually playing (multiplying by fractions). It's apparently OK to have 1.5 times Strength bonus on two-handers, because that calculation is done ahead of time, not in the middle of a fight.
 

Hypersmurf

Moderatarrrrh...
It's apparently OK to have 1.5 times Strength bonus on two-handers, because that calculation is done ahead of time, not in the middle of a fight.

Like, say, Empower Spell?

Let's make that double, as well, for people who can't calculate 150% of 14 in their head...

-Hyp.
 


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