Calculating Pirahna Strike Damage

[Flames of Chaos]

First of all, apologies if this exists somewhere without using the name as I kept trying to find something similar and alls I found were discussions of "MNAAA POWER ATTACK BETTER!!!"

What I need help with is what's on the tin, at least for off-hand attacks:

Pirahna Strike (Combat):
You make a combination of quick strikes, sacrificing accuracy for multiple, minor wounds that prove exceptionally deadly.

Prerequisites: Weapon Finesse, base attack bonus +1.

Benefit: When wielding a light weapon, you can choose to take a –1 penalty on all melee attack rolls and combat maneuver checks to gain a +2 bonus on all melee damage rolls. This bonus to damage is halved (–50%) if you are making an attack with an off-hand weapon or secondary natural weapon. When your base attack bonus reaches +4, and for every 4 points thereafter, the penalty increases by –1 and the bonus on damage rolls increases by +2. You must choose to use this feat before the attack roll, and its effects last until your next turn. The bonus damage does not apply to touch attacks or effects that do not deal hit point damage. This feat cannot be used in conjunction with the Power Attack feat.
---

So if my BAB is 9/4, my full attack bonus is 16/11 (Alchemist with + to Dex mutagen and agile nonsense), and my damage prior to Pirahna Strike is d4+7, which of the following is accurate for my 2 iterative attacks?

A. d20+13 for d4+13 primary, d20+8 for d4+4 (+1 cestus)
B. d20+13 for d4+10 primary, d20+8 for d4+4 secondary
c. d20+13 for d4+13 primary, d20+8 for d4+6 secondary
d. d20+13 for d4+10 primary, d20+8 for d4+4 secondary

I'm asking because my secondary weapon is mithral for dealing with demons/fei, and that's a monster type that is encountered sporadically in large groups so it would be nice to know when I need to bust out the secondary attacks.

Thanks in advance!

[Flames of Chaos]

I should probably add just so it's completely clear: I couldn't afford agile enchantment on both cesti, so only my primary gets to add Dex to damage. My off-hand is a +1 mithral cestus. I'm hoping to eventually add Agile to it as well.

[Cellion]

BAB +9 means your attack penalty is -3 and your damage bonus is +6 with the main hand and +3 with the off hand. Piranha strike applies to all your attacks in the round.

Primary and secondary are terms for natural weapons, not weapon attacks. I think this might be contributing to your confusion. With +9 BAB, you're entitled to two attacks each round. These attacks are treated as main-hand attacks regardless of which weapon you use to make them. So if you use your agile cestus on both attacks, your attack routine looks like +13/+8 (d4+13). You could also make the first attack with the agile cestus and the second with your mithral one, getting one attack at +13 (d4+13), and one at +8 (d4+7). Or you could do both with your mithral cestus.

Again, it doesn't matter which weapon you use, they're all treated as main hand attacks.

If you use two weapon fighting, you can get bonus attacks in a round. These extra attacks are the only things that are treated as off hand attacks. For example, if you have the two-weapon fighting feat, you could make two attacks with your agile cestus as the main hand weapon, and a bonus attack with your mithral off-hand, taking a -2 penalty on all attack rolls (as described in the feat). These three attacks would look like this:

Agile Cestus Main Hand: +11/+6 (d4+7+6)
Mithral Cestus Off-hand: +11 (d4+1+3)

Hope that answers your question.

[vhok]

power attack and pirahna strike only care about your BAB nothing else adds into it. attack bonus is not BAB only BAB is BAB nothing adds to BAB

[Flames of Chaos]

Cellion wrote:

BAB +9 means your attack penalty is -3 and your damage bonus is +6 with the main hand and +3 with the off hand. Piranha strike applies to all your attacks in the round.

Primary and secondary are terms for natural weapons, not weapon attacks. I think this might be contributing to your confusion. With +9 BAB, you're entitled to two attacks each round. These attacks are treated as main-hand attacks regardless of which weapon you use to make them. So if you use your agile cestus on both attacks, your attack routine looks like +13/+8 (d4+13). You could also make the first attack with the agile cestus and the second with your mithral one, getting one attack at +13 (d4+13), and one at +8 (d4+7). Or you could do both with your mithral cestus.

Again, it doesn't matter which weapon you use, they're all treated as main hand attacks.

If you use two weapon fighting, you can get bonus attacks in a round. These extra attacks are the only things that are treated as off hand attacks. For example, if you have the two-weapon fighting feat, you could make two attacks with your agile cestus as the main hand weapon, and a bonus attack with your mithral off-hand, taking a -2 penalty on all attack rolls (as described in the feat). These three attacks would look like this:

Agile Cestus Main Hand: +11/+6 (d4+7+6)
Mithral Cestus Off-hand: +11 (d4+1+3)

Hope that answers your question.

Thanks very much, it does! So it looks like it is -3 for +6 (-1/+2x3) on the main hand and +3 on the off-hand. I wasn't sure if the wording meant the damage overall was halved or just the bonus. And yes, I think I was confusing terms, so thanks for catching that!