How does damage work?

I’m asking about something specific here, but we’ll explore more of it later.

I was farming a stage and using my E2 S2 Eyja. At M3, it has the description of “Deals 370% of ATK Arts damage in the next attack”

Her attack at my level and trust is 686.

In this stage, there is an enemy that has 60 RES.

Guerrilla Shieldguard | Arknights Wiki - GamePress

With me so far? This is a lot of set-up.

I place Eyja, one of those Shieldguards is in range, she does her attack boosted by her S2…and it does 796 damage (you see it bc it shows the number above them).

So does RES reduce damage by 60%? And not a flat 60? That doesn’t make sense, since for physical defense those guys have 1300 and they can’t reduce damage by 1300%. So how does damage work?

(And this can be expanded to how does physical damage work, since someone like Exu does deal barely any but some damage to them and her attack isn’t over 1300; I think I’ve been told there’s a minimum?)


You have it right, defence is a flat number while res is a percentage.
2500 phys atk vs 1300 def: 2500 - 1300 = 1200 damage
2500 arts atk vs 60 res: 2500 - 60% = 1000 damage

The minimum damage is 5% I think. No matter how much def or res they have, an attack can’t be reduced to less than that.


Does Arts damage entirely ignore physical defense?

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That’s pretty much how it works, yes. And yes, Arts damage ignores DEF completely.

Here’s the actual math, which makes me wonder why she’s only dealing 796 damage.

Eyja ATK - 686
S2 M3 - 370%
Eyja Talent - ATK +14% (I’m assuming she’s not Pot6, otherwise it’s ATK +16%) for all Casters on the field

So 686 x 1.14 = 782.04 ATK
782.04 x 3.7 = 2893.548
2893.548 x 0.4 = 1157.4192

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782 attack, 796 damage :feh_lucyshrug:

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This was the first enemy. She had 3 stacks of her fireball when the baddie came out. So shouldn’t the second attack have done more since their RES is -25% for 6 seconds? :thinking:

Or is that only for the people that might have been hit by the fireball as splash damage?

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Weird. I just checked and the Guerilla Herald only buffs ATK and DEF, not RES.

Her debuff only affects the main target, which should be the Shieldguard. Splash damage is half value, but half of 1157 is not 796.

:ak_redwut: :fgo_huh:


The debuff is applied before the damage, so both hits should have the -25% res.


Wait, really? It doesn’t apply after that first hit? :fgo_huh:

Huh… never knew.

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Still, that means the damage should have been higher if the debuff is applied before the damage.


He wasn’t even out yet on the screenshot with the damage shown for the attack, so even if he did it shouldn’t matter

The Sheieldguard is the only target here; does he take splash damage? :feh_confused: I thought there’s only splash to other enemies

But AK has really confusingly worded skills, looking at you “all blocked enemies” :fgo_badciv:


Splash damage is everything except the main target afaik. So it shouldn’t have been hit with an extra attack.

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Ok for this is it -25% of their RES, so in this case 15 (25% of 60)

Or is this a flat reduction, since RES is already a percentage (in this case making it 35%, since 60-25 is 35)

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Funny enough, GP has a similar problem that threw me off just now since I’m making a discussion page for Purestream.

Ptilopsis S2.

2.85 (her base ATK interval) - 1.65 = 1.2 new ATK Interval
Which more or less checks out

Purestream S2

2.85 - 0.12 = 2.63

Me: Wait, this can’t be right. That’s not greatly reduced.
Tries 2.85 x 0.12 = 0.342
Me: Okay, that makes more sense, but why is it phrased the same way?


Aak killed so many Snipers since I thought it was “15 times for 500 total” not “15 times for 500 each


I tried my lvl 50 Eyja and got the exact same result. Every time she does the skill on him, there’s two 796. She shouldn’t be double hitting, right? No idea what’s going on :ak_redwut:



Yeah, I could see how anyone would make that mistake.

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It’s slightly different

One is “by -”
The other is just by

But I’m probably only noticing that bc you said something. I’d be confused otherwise.


Maybe it’s a bug or something with the AoE effect?

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Here’s the thing though. When the phrase is “increase/decrease by” it typically means to add/subtract.

So it made sense in Ptilopsis’ case. Even without the (-), since the ATK interval is reduced then it’s obvious I would subtract that value.

So in Purestream’s case, I saw that there was a value, and that ATK interval is reduced. And the phrasing is exactly the same. Besides which, since the interval is reduced, they obviously aren’t going to say “This Skill modifies the Attack Interval by +0.12”.