How does one determine damage when using the feat Leap Attack?

Question

Just so nobody has to find it, the Complete Adventurer errata says that in the feat Leap Attack that the

second sentence of the Benefit paragraph should read as follows: If you cover at least 10 feet of horizontal distance with your jump, and you end your jump in a square from which you threaten your target, you deal +100% the normal bonus damage from your use of the Power Attack feat.

But does the +100% of the bonus to damage from the feat Power Attack (PH 98) via the feat Leap Attack (CAd 110) interact--due to Dungeons and Dragons 3.X's multiplication rules--with...

1. the feat Power Attack adding twice the attack roll penalty's absolute value as a bonus to damage when using a weapon two-handed?
2. the doubling (or more) damage via a weapon with the weapon special ability valorous (Una 54-5), the feat Headlong Rush (Rac 164), or another means of multiplying damage?

That is, does the feat Leap Attack care if multiplication happens either before or after the feat's effect is determined? Or was the feat deliberately subjected to errata to avoid interaction with the multiplication rules?

Example
A Medium creature with a base attack bonus of +6 and a Strength score of 18 uses a +1 valorous greatsword. The creature charges, satisfies the conditions for the feat Leap Attack, and uses Power Attack to the maximum he's able.

If the creature makes a successful melee attack roll, how much damage is dealt?

Answer 1

This feat is notorious for its poor wording. The “+100%” phrasing is completely unique within D&D 3.5e as far as I know, for example. Ultimately, I can’t imagine any other interpretation here than adding again the number subtracted from your attack rolls, and it does have the nice feature of specifying the “normal” damage from Power Attack which means that features like the frenzied berserker’s supreme power attack that already give one-handed weapons 2:1 returns don’t get doubled to 4:1, but instead go to the 3:1 you would normally expect from D&D’s multiplication rules.

But then there is the line you haven’t quoted:

If you use this tactic with a two-handed weapon, you instead triple the extra damage from Power Attack.

No bizarre “+100%” in sight! But also we have lost the useful reference to “normal” and now it is multiplying “the extra damage from Power Attack,” whatever that is for you. This is going to get us in trouble, you can just tell already.

So you are tripling the extra damage—not tripling the penalty applied. The problem here, well the first problem here, is that “the extra damage from Power Attack” is “twice the number subtracted from your attack rolls” when attacking two-handed. Worse, since “the extra damage from Power Attack” is calculated as twice the penalty, but isn’t itself subject to any multiplier, arguably the repeated-multiplication rules don’t apply, and that gets you a 2×3=6 rather than 1+(2−1)+(3−1)=4. So instead of 2:1 returns on Power Attack, you get 6:1 returns on Power Attack. Or maybe you get 5:1; it’s impossible to say since it’s worded so poorly. Plus, ya know, I suspect what they meant to do was give you 3:1 returns, but of course they didn’t say that.

And that would combine quite nicely with, say, the supreme power attack feature of the frenzied berserker, who was getting 4:1 returns to begin with. Now they’re arguably getting 8:1.

On top of those issues, this is only the Power Attack bonus damage. The result is added to the rest of your damage, and that gets you your full damage... which might be multiplied again, e.g. with valorous. This effectively multiplies your multiplier, which is exactly what the multiplication rules try to avoid, but since two different things are being multiplied, the multiplication rules don’t actually come into play.

So for the example: 2d6+1 damage from the weapon itself, +6 for Strength, and the −6 attack penalty for maximum Power Attack results in double that for +12 damage from Power Attack without Leap Attack. Thus 2d6+19 is the baseline for all interpretations, and valorous doubles that for 4d6+38.

With the 6:1 returns, we are instead looking at Power Attack bonus of +36 (six times the penalty, triple “the extra damage from Power Attack” which would have been +12). Using 5:1 brings that down to +30, which is somewhat better, but not, ya know, great, when what they probably meant was +18. Note that +36 is nearly what valorous was giving the entire attack before. Now with valorous, we’re looking at a total of 4d6+66—of which, 52 comes from Power Attack.

It may not be a bad idea to try to eliminate the multiplication of a multiplier here through houserule, but note that the Power Attack bonus damage isn’t the only case of this: the bonus damage due to Strength also has a multiplier, +1½×, which is also being doubled by valorous. This, unlike Leap Attack, has strong precedent in the rules. The “fix” would be to apply the multiplication rule individually to all sources of damage, like so:

\begin{array}{r} 2 \times ( && 2\text{d}6 && +1 && +1\tfrac{1}{2}\times 4 && +3\times 2\times 6 & ) \\ = && 2\times 2\text{d}6 && + 2\times 1 && + 2\times 1\frac{1}{2}\times 4 && + 2\times 3\times 2\times 6 \\ = & [1 \\ && +\left(2-1\right) \\ & ] & \times 2\text{d}6 & +[1 \\ && && +\left(2-1\right) \\ && & ] & \times 1 & +[1 \\ && && && +\left(2-1\right) \\ && && && +\left(1\frac{1}{2}-1\right) \\ && && & ] & \times 4 & +[1 \\ && && && && +\left(2-1\right) \\ && && && && +\left(3-1\right) \\ && && && && +\left(2-1\right) \\ && && && & ] & \times 6 \\ = && 2\times 2\text{d}6 && +2\times 1 && +2\frac{1}{2}\times 4 && +5\times 6 \\ = && 4\text{d}6 && +2 && +10 && +30 \\ = && && && && 4\text{d}6+42 \\ \end{array}

But this is very-definitely a houserule, and I’m not convinced that it is good (I mean, good luck calculating that for every attack!), even though it “enforces” the idea that you’re not supposed to get to mulitply multipliers.

Answer 2

Just to TL;DR KRyan's excellent answer, you can think of it like this.

Normally, in DnD, you add all the multipliers together minus the principal, so x2 and x2 become x3, so forth.

Leap Attack is worded really weirdly, so it doesn't x2, it says 'take the power attack damage number, and then add it to your total damage again' and so by RAW avoids the multiplication rules. Technically, yes, that is multiplication, but it doesn't use the 'x2' or 'multiply' words so we can't apply the multiplier rules to it by RAW.

Since it's adding, it avoids multiplication entirely, which is why it's so popular for 'Charger' builds - it adds to the 'base damage' and so gets multiplied by all the multipliers - Heedless Rush, Valorous, Vaulting, Battle Jump, Spirited Charge, Deadly Charge, etc. When your base damage is 1d8+10, x6 is 87 damage, but when your base damage is 1d8+20, x6 is 147, or, noticeably larger.

Charger builds love base damage, and Leap Attack adds a lot.

Answer 3

Both above examples are very inline with the issue. A simple (well, not simple, but GM rules argument free way to rule it!) is this; The Leap Attack Doubles the power attack damage as a x2 multiple on its own. and if you have a valorous weapon that then doubles it again, so doubling a doubling run goes into effect. I will show a example below. And if a Critical weapon hit is added for another doubling or Battle jump, ect. you keep with the multiplier rules. Example;

Level 8 Human, Jotunbrud, Shock Trooper, Pounce; Charging +Valorous Weapon +Rhino’s Charge spell +crit??.
Strength of 26. Damage; Large greatsword, 2 handed. +1 with Valorous enhancement and Keen (+3 total enhancement). (Do the math if you add more doubling or damage levels, ect.)

3d6 wpn +12 str. +1 magic +3 buff spell (you should have something up I hope) +16 (P.A. 8 x2 -> leap attack feat) = 3d6 +16 +16 Dam hit. Total average damage = 42 Dam

(A 1d6 damage average of 3.5 used to give a total damage example rounding down per RAW.)

x2 - Valorous Weapon bonus (So doublilng the Leap attack on its own makes it x3) 3d6 wpn +12 str. +1 magic +3 buff spell +16 x2 +(P.A. 8 x3 -> leap attack feat) = 6d6 +32 +24 Total average damage = 77 Dam

x2 – Rhinos Charge spell
3d6 wpn +12 str. +1 magic +3 buff spell +16 x3 +(P.A. 8 x4 -> leap attack feat) = 9d6 +48 +32 Total average damage = 111 Dam

x2 – Critical Hit
3d6 wpn +12 str. +1 magic +3 buff spell +16 x4 +(P.A. 8 x5 -> leap attack feat) = 12d6 +64 +40 Total average damage = 146 Dam

Doubling a Doubling multipliers per RAW; ( x2x2=x3 ) & ( x2x2x2=x4 ) & ( x2x2x2x2=x5 ) Ect..

The below listed adds are damage adders and not part of the weapons damage, so they do not get all the Doublings (If I have this wrong, please let ME know ASAP, I am missing some splatter fun otherwise.!) +2d6 (Rhino hide Armor) +2d6 (powerful charge feat) if you have them.