Previously I made a guide on the 57 Leaf Clover.
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=2387506982
So it only makes sense to talk about the opposite item now. Purity.

Not really an item considered to be very good. But how bad is it exactly?

Let's go do some maths.

Reducing all skill cooldowns by 2 seconds is obviously pretty good.
But as you probably already know, there is a payoff. Purity makes you unlucky.

It works just like the 57 Leaf Clover and effects the same things (see 57 Leaf Clover guide) but in the opposite way. The 57 Leaf Clover re-rolls random effects for a favorable outcome while Purity re-rolls random effects for an unfavorable outcome.

Sounds similar enough right?
Well the maths works a bit differently.

Time to look at some probability trees again.



Okay let's say you're using AtG Missiles.
They have a 10% chance to activate.

The probability tree would look like this:


1 out of 10 chance that it will activate and 9 out of 10 that it won't.

If you have a 57 Leaf Clover then every time that your AtG Missiles don't activate, you'll have another 1 in 10 chance to activate them.


1/10 + 9/10 * 1/10 = 19/100 or 19%
So with one 57 Leaf Clover your chance to activate AtG Missiles becomes 19%



Purity does the opposite:


If you get the 1 in 10 chance to activate your AtG Missiles, the Purity will try to re-roll the outcome so you'll have to get the 1 in 10 chance again to activate the AtG Missiles.

1/10 * 1/10 = 1/100 or 1%
Which means that having a Purity reduces your chance from 10% to 1%



Okay so a 57 Leaf Clover doesn't even double your luck while a Purity makes it 10 times worse.
So it seems like Purity makes you much unluckier than a Clover makes you luckier.
But why?

Imagine you're throwing dice. And to activate your item you need to roll a 6.
If you have a Purity, now suddenly you have to roll 6 twice in a row to activate it.

Usually your chance to roll a 6 is 1 out of 6.
Rolling 6 twice in a row is 1 out of 6 times 1 out of 6.
1/6 * 1/6 = 1/36

Having to roll 6 twice instead of just once makes it significantly harder to activate items.
This is what Purity does. You'll have to roll every effect twice in a row to activate it.

Well... if you pick up a Purity, you're not going to be activating stuff like AtG Missiles, Ukuleles, Molten Perforators, Sentient Meat Hooks, etc.

It's not really "oh I'm going to activate my items less often if I pick this up'' but more like "i'm basically not going to activate my items at all"
Even if you just pick up one, the chance to activate most items just gets too low.

However, if your activation chance for an item is very high initially then it's not that bad.
Let's say you have 6 Tri-Tip Daggers with 15% chance to activate each, which adds up to 90%
9/10 * 9/10 = 81/100 or 81%

This is... not that big of a decrease honestly.

Generally, the higher the initial activation chance the smaller the decrease.
And if you manage to reach 100% chance to activate something then Purity doesn't have an impact.

So if you have high Critical Strike chance, Tri-Tip Daggers, Sticky Bomb, etc. then it's not that bad.
For those items obviously. Because your AtG's and Ukuleles are still going to be useless.



Aditionally, cooldowns can only be reduced to a minimum of 0.5 seconds.
So you won't even be able to just spam abilities with Purity.



One more thing that could be done is to have both a 57 Leaf Clover and a Purity.
Having an equal amount of Clovers and Purities will cancel out their effects.

But if you have good items you want to be activating then wouldn't it just be better to use the effect of the 57 Leaf Clover and activating your items more instead of having a skill cooldown reduction?



Overall, Purity is just really bad except in some specific cases (which i'll get into in a moment).

I'm not going to go as in-depth with the numbers as in my 57 Leaf Clover guide.

I think that calculating every item with just one Purity is more than enough because if you have multiple Purities, I don't think you're planning to activate any items anyway.


AtG Missile Mk. 1:
10% → 1%

Ukulele:
25% → 6.25%

Molten Perforator:
10% → 1%

Charged Perforator:
10% → 1%

Happiest Mask:
7% → 0.49%

Brittle Crown:
30% → 9%

Tri-Tip Dagger:
(note: got changed in the anniversary update from 15% to 10%)
10% → 1%
20% → 4%
30% → 9%
40% → 16%
50% → 25%
60% → 36%
70% → 49%
80% → 64%
90% → 81%
100% → 100%

Sticky Bomb:
5% → 0.25%
10% → 1%
15% → 2.25%
20% → 4%
25% → 6.25%
30% → 9%
35% → 12.25%
40% → 16%
45% → 20.25%
50% → 25%
55% → 30.25%
60% → 36%
65% → 42.25%
70% → 49%
75% → 56.25%
80% → 64%
85% → 72.25%
90% → 81%
95% → 90.25%
100% → 100%

Stun Grenade:
(hyperbolic scaling see clover guide for more info)
4.76% → 0.23%
9.09% → 0.83%
13.04% → 1.7%
16.67% → 2.78%
20.00% → 4%
23.08% → 5.33%
25.93% → 6.72%
28.57% → 8.16%
31.03% → 9.63%
33.33% → 11.11%
35.48% → 12.59%
37.50% → 14.06%
39.39% → 15.52%
41.18% → 16.96%
42.86% → 18.37%
44.44% → 19.75%
45.95% → 21.11%
47.37% → 22.44%
48.72% → 23.74%
50.00% → 25%

Bandolier:
(special scaling see clover guide for more info)
20.45% → 4.18%
30.41% → 9.25%
36.71% → 13.48%
41.21% → 16.98%
44.64% → 19.93%
47.38% → 22.45%
49.65% → 24.65%
51.57% → 26.59%
53.23% → 28.33%
54.67% → 29.89%
55.96% → 31.32%
57.11% → 32.62%
58.14% → 33.80%
59.08% → 34.90%
59.95% → 35.94%
60.74% → 36.89%
61.47% → 37.79%
62.15% → 38.63%
62.79% → 39.43%
63.38% → 40.17%

Old War Stealthkit (outdated):

The item got changed in the Anniversary Update.

It used to have a chance of activating depending on how much damage you took.
Now it activates when falling below 25% health and is no longer effected by luck.

Ghor's Tome:
4% → 0.16%
8% → 0.64%
12% → 1.44%
16% → 2.56%
20% → 4%
24% → 5.76%
28% → 7.84%
32% → 10.24%
36% → 12.96%
40% → 16%
44% → 19.36%
48% → 23.04%
52% → 27.04%
56% → 31.36%
60% → 36%
64% → 40.96%
68% → 46.24%
72% → 51.84%
76% → 57.76%
80% → 64%
84% → 70.56%
88% → 77.44%
92% → 84.64%
96% → 92.16%
100% → 100%

Sentient Meat Hook:
(hyperbolic scaling see clover guide for more info)
16.67% → 2.78%
28.57% → 8.16%
37.50% → 14.06%
44.44% → 19.75%
50.00% → 25%
54.55% → 29.76%
58.33% → 34.02%
61.54% → 37.87%
64.29% → 41.33%
66.67% → 44.45%
68.75% → 47.27%
70.59% → 49.83%
72.22% → 52.16%
73.68% → 54.29%
75.00% → 56.25%
76.19% → 58.05%
77.27% → 59.71%
78.26% → 61.25%
79.17% → 62.68%
80.00% → 64%

Spinel Tonic:
(unfavorable effect so chance increases)
20% → 36%

Critical Strike chance:
(base 1% chance + items)
1% → 0.0001%
6% → 0.36%
11% → 1.21%
16% → 2.56%
21% → 4.41%
26% → 6.76%
31% → 9.61%
36% → 12.96%
41% → 16.81%
46% → 21.16%
51% → 26.01%
56% → 31.36%
61% → 37.21%
66% → 43.56%
71% → 50.41%
76% → 57.76%
81% → 65.61%
86% → 73.96%
91% → 82.81%
96% → 92.16%
100% → 100%

Flamethrower:
50% → 25%

Let's say you're going for Mithrix.

You're on the final stage now and you weren't lucky enough to get any AtG Missiles but you have a couple of Ukuleles and 10 Tri-Tip Daggers. You also got a Happiest Mask.

You went and opened the Lunar Pods and a Purity popped out.
Well... you should probably take it.

The Ukuleles and Happiest Mask probably won't do much during the Mithrix fight.
You have 10 Tri-Tip Daggers which add up to a 100% chance to bleed enemies.
So why not reduce your skill cooldowns by 2 seconds?



Generally, if you're planning on ending a run and don't have very important items you want to activate or have a high activation chance on items that stack then taking a Purity probably won't hurt.

Even if you're not going to Mithrix but are planning on obliterating soon, missing out on something like Ghor's Tome isn't going to ruin your run.



If you want to use Purity or not really just depends on the loot you have and on the loot you're planning on getting. If you're close to ending your run and you don't have AtG Missiles then you probably won't get any more AtG Missiles. Then sure, go take the Purity.
But if you see a Purity at the Bazar after stage 2 and don't have items to activate, it doesn't mean that you're not going to gain those items later and regret picking up Purity.

Just look at your items, look at how far into the run you are and decide if picking up a Purity is a good idea.



Alternatively, what if you don't really need on-hit items like Ukuleles and AtG Missiles?
What if you're going for a different build from the start?

Loader isn't that good with on-hit items. She hits hard but not often.
The Bands (Runald's Band and Kjaro's Band) are much more useful to you than Ukuleles.

Overall, when playing Loader you'll probably benefit more from skill cooldown reduction than on-hit items. You could pick up a Purity early in the run and just ignore the luck based items as they won't do much for you even without the Purity. Go for movement items, healing or something more defensive and focus on stuff like the Band as your damage items.

Other survivors that could be considered are Mercenary, Artificer and in some cases Acrid.

Multiplayer has some interesting implications for Purity.

What if the other players benefit benefit a lot more from on-hit items than you?
Then the items aren't going to waste. AtG Missiles will still be firing. Just from a different source.



Let's say you're playing Artificer. Artificer isn't very good with on-hit items in the first place so why not give them to your friends which will be able to use them much more effectively.
Instead, take a Purity.

Firstly, it will reduce your primary cooldown from 1.3 to 0.5 seconds. But secondly, Artificers skills are very very powerful.

Flamethrower: you can use it every 3 seconds now.
Charged Nano-Bomb: strong aoe every 3 seconds.
Snapfreeze and/or Cast Nano-Spear: you freeze things way more often which benefits everyone.
Ion Surge: ehm... yes!

Artificer benefits more from the cooldown reductions and other characters benefit more from the items. Win-win!



Or if you're playing Acrid (as has been pointed out to me in the comments).

Yes you can make some insane proc chains with his Epidemic ability but survivors with just a better primary in general will probably activate the items more often.

If you can Get your hands on 10 Tri-Tip Daggers then they're not effected by Purity as they would have a 100% chance of applying bleed and in combination with items like Gasoline or Will-o'-the-wisp which activate on kill, you can easily deal with large groups of enemies with Epidermis which you can now use every 8 seconds.

You're secondary Neurotoxin now also has a cooldown of 0.5 seconds so it can basically always be used. Why would you even use your melee attack anymore?



So if you're playing multiplayer, think about if the other players will be more effective with the on-hit items and think about how much you're going to benefit from cooldown reductions.

Thank you for checking out this guide.

Again, if you see any mistakes in any of my calculations or anything else please let me know so I can correct them.

I hope you now know how bad Purity exactly is and when it might be not as bad and I wish you lots of Lunar Coins in your runs. (unless you edit them in then i wish you lots of lunar altars idk)