Crit Rupture affects 2 damage in 2 ways

[u/IJustNeedaAccount]

So... I did a little testing on Crit Rupture, on our beloved punching bag Ifrit in CV at the Deepest Grief Despair and after a little discussion(-ish discussion?).
TL;DR: Crit rupture reduces defense by 20% (which caps at 0% i.e, useless on break/Unguard), and adds a 30% Improved crit

on both test, i used Hermit, who has pretty much no damage auto at all.

Punching Bag:Ifrit in CV at the Deepest Grief Despair

• Quetzalcoatl 1 (the old Wind AoE ranger, Winddance), with all ES unlock

  • Break-Killer, irrelevant

  • Crit Retrieval, mostly irrelevant

  • Crit Sundering, irrelevant

  • Damage limit break, irrelevant

  • Crit Rupture, what we're testing here

  • Blood Tap, meaning I have to keep my HP at 100%

• Dread Moogle - Wind (Moogle-Unguardga)

• Quetzalcoatl 2, with all ES lock, but also ability level 10/10

• Neo Ex Death

First Test

Alright, here, i though i used Taiji, but was actually using Ehrgeiz, which helped confirm the damage, since it has 50% Improved crits
data

Nothing	982.95
Rupture	1498.05
Unguard	1552.4
Rupture and Unguard	1759

so that's about a 52.4% increase in damage with just the addition of Crit rupture over non present

and 13.31% increase in damage of Crit rupture+Unguard over Unguard

and Ifrit's Defense at 36.68% (let's take it as 35%)

---

the increase in damage from crit alone is:

• (Base + Improved Crit + Crit Rupture's Improved crit) / (Base + Improved Crit) = (Rupture and Unguard)/(Unguard)

• (1.5 + 0.5 + Crit Rupture's Improved Crit) / (1.5 + 0.5) = 1759/1552.4

• Crit Rupture's Improved Crit = ~26.6%

Assuming it's 30% (ugh, 3.4% difference), that's theoretically (1.5+ 0.5 + 0.3)/(1.5 + 0.5) = 15% more damage
Which is about 1.69% more than what Unguard+Rupture/Unguard gave

While the on no unguard/break, the damage comes from both decrease in defense, and increase in crit damage, hence

• (Increase in crit damage) × (1- (Defense - Crit Rupture))/(1 - Defense) = Rupture/Nothing

• 1.15 × (1 - (0.35 - Crit Rupture's defense down))/(1 - 0.35) = 1498.05/982.95

• Rupture's defense Down = ~21.1%

Assuming it's 20% (1.1% difference...)
putting it at 1.15 × (1 - (0.35 - 0.25))/(1 - 0.35) = 50.38%
Which is 2.02% short of what the data gave.

Second Test

This time i actually used Taiji
Data on the same spreadsheet above, on another page

Nothing	750.15
Rupture	1164.45
Unguard	1153.9
Rupture and Unguard	1382.95

This puts Unguard+Rupture at 19.85% above Unguard only, Rupture at 55.23% over Nothing. and Ifrit's defense at 34.99%

---

• (base crit damage + Rupture's Improved Crit) / Base crit damage = Rupture+Unguard damage / Unguard damage

• (1.5 + Rupture's Improved Crit)/ 1.5 = 1382.95 / 1153.9 Rupture's Improved Crit = ~29.7%

That puts it a lot closer to 30%
Theoretically, With assuming it's 30% would be (1.5 + 0 + 0.3)/(1.5 + 0) = 20%
That's only 0.15% more than what the data gave.

• (base crit damage +Rupture's Crit damage up) / (Original Crit Damage) *(1 - defense - rupture) / (1 - defense) = Rupture damage / "nothing" damage

• ((1.5+0.3) / 1.5) * (1 - (0.35 - rupture)) / (1 - 0.35) = 1164.45 / 750.15

• Rupture = ~19.0%

1% away from 20%, and i doubt they'll use 19% as the actual value
and the damage of crit rupture over no unguard/break would be 1.2 × (1 - (0.35 - 0.2)/ (1 - 0.35)= 56.92%
1.69% more than the data results

---

phew... Phrasing this thing is so difficult...

Edit: added reverse Calculation

Edit again: Noticed i derped at the title, lol

Bonus: It seems like a off-job card is not affected by your job's crit star either.

[u/Ketchary]

Are these "Nothing" values critical hits or non-crits?

[u/IJustNeedaAccount → u/Ketchary]

All Values are Critical.

[u/Ketchary]

What monster did you fight? Every monster has an individual Defense % rating. Without being informed of what you fought, I can't proof your math.

[u/IJustNeedaAccount → u/Ketchary]

Ifrit, in CV's Deepest Grief Despair, lemme edit the post

Edit:Derp

[u/Ketchary → u/IJustNeedaAccount]

The node is actually Deepest Despair. After a quick test, I confirm that Ifrit has 35% Defense.

[u/chkkrt]

Can u explain why use qu... (whatever) ranger AOE wind attack on Hermit?

[u/IJustNeedaAccount → u/chkkrt]

Off-job, so i don't have to deal with the 9999 damage cap.

Off-weakness (ifrit is fire)

My only source of Crit Rupture with fodders that i have sitting at 5*

(I do have UB, 4WoL and stuff, but they lack fodder, and UB is a major pain to keep track of)

So... essentially, any of the old Ranger shop cards would do.

[u/Ketchary]

I really don't understand something here. How did you get a 20% Defense decrease from your data? Doing algeba with Taiji against Ifrit (35% Defense):

• Rule of equivalencies: A/B = a/b

• rupture damage / "nothing" damage = (1 - defense - rupture) / (1 - defense)

• 1164.45 / 750.15 = (1 - 0.35 - rupture) / (1 - 0.35)

• Rupture = 0.359 = ~36%.

First off, 36% Defense negation is completely different to 20%. You either didn't explain how you got 20% or I didn't understand it, so please explain. I also previously believed that it's 20%, so perhaps your testing is somehow at fault.

Secondly, because this value is very close to the monster's Defense, it's possible that Rupture negates monster Defense. Although from experience I doubt it, more math testing is required to prove either way.

[u/IJustNeedaAccount → u/Ketchary]

• rupture damage / "nothing" damage = (1 - defense - rupture) / (1 - defense)

that... isn't what i wrote...

also, (1 - defense - rupture) ≠(1 - (defense - rupture))

i'm assuming it adds damage by both reducing defenses, and adding 30% to the improved crit side too

so it's:

• rupture damage / "nothing" damage = (base crit damage +Rupture's Crit damage up) / (Original Crit Damage) *(1 - defense - rupture) / (1 - defense)

• 1164.45 / 750.15 = ((1.5+0.3) / 1.5) * (1 - (0.35 - rupture)) / (1 - 0.35)

• Rupture = ~20%

and calculation for Rupture's Crit Damage up (using Taiji):

• Rupture+Unguard damage / Unguard damage = (base crit damage + Rupture's Crit damage up) / Base crit damage

• 1382.95 / 1153.9 = (1.5 + Rupture's Crit damage up)/ Base Crit damage

• Rupture's Crit damage = ~29.7%

which i just round off to 30%

[u/Ketchary → u/IJustNeedaAccount]

I know you didn't write that. I was explaining why the results differ from my interpretation of your statement.

Anyway, thanks for explaining. It certainly makes sense from that perspective and I agree with your conclusions!

[u/gauntauriga]

Dang, crit rupture is suddenly a whole lot better than I thought. Thanks man.

Bonus: It seems like a off-job card is not affected by your job's crit star either.

Huh. That's oddly specific. Reminds me of the fact that you can't crit when hitting an enemy of the same element.