Favored Power Attack & Leap Attack Stack?

[fluffy32]

Power Attack: penalty to attack roll up to your BAB and add to damage. If wielding 2 hand weapon, damage is doubled.

Favored Power Attack[FPA] (Complete Warrior 98): When using power attack against Favored Enemy, subtract number from attack bonus and add double to damage. If wielding 2 hand weapon, damage is tripled.

Leap Attack[LP] (Complete Adventurer 110): Combine jump of @least 10ft w/ charge, double damage from power attack. If tactic used w/ 2 hand weapon, triple power attack damage.

Assuming we have a 10 Ranger human w/ great sword, Power Attack, Favored Power Attack, Leap Attack, and Favored Enemy: Giants +6 FIGHTING a giant....

On first thought, I would x6 power attack damage(x3 + x3). However, both FPA and LP seem to increase power attack damage based on whether the character is wielding a 2 handed weapon. So then I think x4 power attack damage(doubled for 2handed, tripled for FPA, quad for LP). What do you all think the total power attack damage boost should be with these 2 feats combined?

Example: assuming sample Ranger mentioned above has: +2 great sword, Str. 22, -5 penalty w/ power attack...Successful jump & charge...
Attack +13(10bab+6str+2weapon-5powerA)
Damage 2d6+9(str) +6(favored enemy) +20(LP & FPA w/ 5 base boost)+2weapon =2d6+37!!!!

[jiriku]

It works about like you're hoping. Add Frenzied Berserker to the mix for further shenanigans. Be mindful, though, that if your damage output significantly outpaces that of other party members, or puts you in the league of one-shotting any sort of reasonable opposition, you can very easily wreck party balance by stacking these things. In that situation, the DM will really have no choice but to respond by either a) causing your favored enemies to never appear as opponents, resulting in a wasted feat or b) hit you with a bunch of enemies using this exact trick stacking Favored Enemy: <your race here>, resulting in your character being dead.

[bekeleven]

D&D works like FPUs: All multiplication is secretly addition. "Double" is just "Add it again" and "Triple" is "Add it twice."

So two-handed power attack = x2. Favored Enemy Power Attack is +1X. Leap attack is +1X.

X4 is the total.

[Baroknik]

D&D works like FPUs: All multiplication is secretly addition. "Double" is just "Add it again" and "Triple" is "Add it twice."

So two-handed power attack = x2. Favored Enemy Power Attack is +1X. Leap attack is +1X.

X4 is the total.

This except you may be able to argue x5 since Leap Attack reads to count 2H as an additional increase.

[Andezzar]

D&D works like FPUs: All multiplication is secretly addition. "Double" is just "Add it again" and "Triple" is "Add it twice."

So two-handed power attack = x2. Favored Enemy Power Attack is +1X. Leap attack is +1X.

X4 is the total.No. Using a two-handed weapon with power attack does not double the damage you would get with a one-handed weapon. It gives you a different exchange rate of attack penalty to extra damage, which just happens to be 1:2.
If you attack with a two-handed weapon, or with a one-handed weapon wielded in two hands, [u]instead add twice the number subtracted from your attack rolls.

Favored Power attack also gives you new exchange rates, it does not modify the usual ones. 1:2 for one-handed weapons, 1:3 for two-handed weapons.

Leap attack functions differently. It adds +100% of the power attack damage with a one-handed weapon and triples the damage from power attack with a two-handed weapon.

So favored leap attack power attack is +9 damage per -1 to attack.

[Curmudgeon]

So favored leap attack power attack is +9 damage per -1 to attack.
That doesn't accord with D&D math. Two triplings don't give x9.
Multiplying

Sometimes a rule makes you multiply a number or a die roll. As long as you’re applying a single multiplier, multiply the number normally. When two or more multipliers apply to any abstract value (such as a modifier or a die roll), however, combine them into a single multiple, with each extra multiple adding 1 less than its value to the first multiple. Thus, a double (×2) and a double (×2) applied to the same number results in a triple (×3, because 2 + 1 = 3).

[Grooke]

*4 is the general consensus. Any other interpretation the DM is willing to accept can work for your table. Heck if goes with *9, go Shock Trooper and insta-kill anything to see how long that stays fun.

[Necroticplague]

That doesn't accord with D&D math. Two triplings don't give x9.

Except his point is that it's not tripling twice. Leap attack is the only tripling being done here. The point is that favored power attack makes you have a 3:1 damage ratio, and Leap Attack multiplies it by 3. Assuming a two handed weapon is used.

[Andezzar]

Necroticplague was faster. I totally agree with his assessment.

[Curmudgeon]

Except his point is that it's not tripling twice. Leap attack is the only tripling being done here. The point is that favored power attack makes you have a 3:1 damage ratio, and Leap Attack multiplies it by 3. Assuming a two handed weapon is used.
I believe the distinction is entirely semantic.

If you are using a two-handed weapon, add 3 times the number.
That's still a multiplication, and D&D multiplication rules apply unless it's a real-world value.

[Andezzar]

"the number" does not refer to the extra damage but to the number subtracted from the attack. This number gets multiplied once. Then Leap Attack multiplies the extra damage which is a different statistic. So you do not have multiple multiplications of one statistic but single multiplications of two different numbers. Thus D&D multiplication does not apply.

[Curmudgeon]

"the number" does not refer to the extra damage but to the number subtracted from the attack. This number gets multiplied once. Then Leap Attack multiplies the extra damage which is a different statistic. So you do not have multiple multiplications of one statistic but single multiplications of two different numbers. Thus D&D multiplication does not apply.
It's not a different statistic; "the extra damage from Power Attack" is identical to "3 times the number". It's just a new intermediate variable introduced (a new name), but the D&D multiplication rules don't care about names unless they're associated with real-world values.

[Andezzar]

No, D&D multiplication only applies if you multiply the same modifier or die roll more than once. Favored power attack does not modify the extra damage from power attack but changes the formula to calculate the extra damage. Leap attack then modifies the extra damage from power attack.

[atemu1234]

No, D&D multiplication only applies if you multiply the same modifier or die roll more than once. Favored power attack does not modify the extra damage from power attack but changes the formula to calculate the extra damage. Leap attack then modifies the extra damage from power attack.

Yes, this one seems to follow normal mathematical laws.

[Curmudgeon]

No, D&D multiplication only applies if you multiply the same modifier or die roll more than once.
That's a limitation you've added, not what's in the rules.
Multiplying

Sometimes a rule makes you multiply a number or a die roll. D&D multiplication rules apply if you multiply a number. The formula for extra damage in Favored Power Attack involves multiplying a number. Leap Attack multiplies that result. It's successive multiplication of a number, with just some semantic misdirection thrown in.

[Andezzar]

What you quoted says nothing about what to do when you multiply a number.
As long as you’re applying a single multiplier, multiply the number normally. When two or more multipliers apply to any abstract value (such as a modifier or a die roll), however, combine them into a single multiple, with each extra multiple adding 1 less than its value to the first multiple.The number subtracted from the attack is one abstract value, the extra damage from power attack is a different one. That the extra damage from power attack sometimes is calculated by multiplying the number subtracted from the attack by three, does not not make it the same abstract value.

Or to put it differently favored power attack multiplies the attack penalty (to be exact the absolute value of the attack penalty), which is one modifier and Leap attack multiplies the extra damage from power attack which is a different modifier.

[Curmudgeon]

What you quoted says nothing about what to do when you multiply a number. The number subtracted from the attack is one abstract value, the extra damage from power attack is a different one.
That there's a "different abstract value" doesn't affect the rule. You're multiplying one abstract value (the number subtracted from your attack roll) by 3, then again by 3. If there were some other arithmetic process involved then it wouldn't simply be two or more multipliers. However, there is no intermediate step other than in naming.

[fluffy32]

Well, I'm going w/ x4. As the DM in my campaign, an NPC w/ this combo is going to hit hard. The Frenzied Berserker is a great idea! I had completely forgot that prestige class boosted power attack(and I played a berserker as a player for several months in a previous campaign). Although, with the feat requirements(Power Attack, Cleave, Destructive Rage, Intimidating Rage)-it'd be a bit of multiclass to get supreme power attack before ECL was 20. A 5 Ranger/1 Barbarian human would be awesome. I would do 5 Ranger/1Barb instead of 5 Barb/1 Ranger since more ranger gives higher favored enemy boost as opposed to relying on barbarian rage which lowers AC and has limited usage.

I'll probably end up making x2 NPCs w/ Leap Attack & Favored Power Attack; a Barb/Ranger/Frenzied Berserker and a Barb/Ranger/Bear Warrior.

Thanks for the comments everyone! Happy rolling!