RETRACTED THE ORIGINAL BUG REPORT
There is no Bug. Chantodo’s Resolve is nerfed by the scalar 4/7 ~= 0.571428571428.....
Credits to TinneOnnMuin with his findings.
Join the Feedback Discussion: Chantodo's feedback: change how the nerf is implemented - #10 by TinneOnnMuin-1187
Surprised no one has commented but some very nice research there sVr! 
Thanks for testing.
It is very bad desing of nerf.
Yellow elite with very low hp remaining: With 5 APS is possible to wait more time to kill it than with lower APS…
And for low difficulties is very bad too. It can be overall better play with lower AS in low difficulties.
I don’t see why they don’t use:
Hi sVr! First off, thank you for the testing. 
I have not yet performed a similar test, with just the Chantodo’s worn (no vyr), where I would be able to reference damage numbers like you have in the OP.
However, I took footage of several Low GR runs (GR70s at a power level equivalent to 1700 paragon augmented) with the Cold Vyr Chantodo build.
The point of this test was pretty simple:
This makes it really easy to see if an enemy gets hit or not.
In my testing, I would confirm 5 APS before entering a new archon, and then commence running / teleporting through the rift without attacking, except for the Wave of Destruction from Chantodo’s, for that test rotation.
In result, I could not confirm the issue you’ve noted in the OP as yet.
Aside from those monster types that ‘suspend’ at 1hp and don’t die unless they get hit twice (think about grotesque, legionnaire mob, etc.), or don’t die quickly (Some death animations were longer than others), all monsters within the WoD radius were getting hit and almost all were dying from the Chantodo’s wave.
Ran with: damage numbers enabled, enemy heath enabled. Almost every enemy at this low of density was displaying a damage number upon getting hit from the WoD in this test.
There were a few fringe cases where mobs hitbox was near the edge of the wave, and the display of the wave appeared to reach them, but the game counted the WoD as not hitting them.
This is possibly because I was moving, and where the server says I was vs where the client showed I was might have been slightly off, or perhaps, the WoD origin point was out of sync with it’s display. In these cases, the mob did not take damage, which… could be expected.
As far as density goes, there were several situations where I had 15-30 monsters around. Most engagements in this test set were with less than 15 though.
Granted, this is not near the density you had in your testing, or that we might see on a push. However, if such a dynamic proc coefficient were in place, I would expect repeated tests of 20+ mobs to produce some misses every now and again while I am at 5 APS. This was not the case.
Testing performed on PTR non-seasonal 2.6.7.63266.
Of note, I did review the damage display on some of my 125 clears on the PTR. Damage from the Wave of Destruction does not seem to be displaying similarly at really high density as it does at low density. I’ll note maybe a few numbers from the WoD (3-6) even though there are about 30-50+ mobs around. I am using the punch || beam, && blast attack in addition to the WoD there though.
Perhaps this is just an issue with damage display for the Wave of Destruction numbers at really high density (~30-50+) and/or when other attacks are performed at the same time, and the nerf is impacting the build via some other method?
Or perhaps the issue is limited to situations of very high density?
Ty for testing and replying Cratic. I retracted my initial report.
It’s official then - I have no clue how this nerf was put into place and why I am still able to “proof that a 5.0 multiplier” is still in place. Right now I am out of ideas how and what to test.
Oh goodness me! I’m at a loss there as well. Vyr is so hard to test numbers with when you have it equipped.
I don’t doubt your numbers (though I should check them, would be good practice…
). Usually if there is this much confusion on something it’s because it was designed in such a complex or confusing manner. The change could be coded to only affect certain gear loadouts, or it could be tied to things we aren’t aware of as yet.
I’ll see if I can get a better read on the damage numbers as compared to live at certain stack counts. The damage display I believe has always had some trouble when you get to attacking so quickly, and hitting so many monsters.
I’m definitely open to alternative ideas on how to test this.
It’s possible we may not get a definitive answer through this kind of testing though, simply due to how complex the build is.
Perhaps this is just a case where we need some communication. Both on how exactly the nerf was implemented, and how we should best go about confirming it.
I believe the tooltip for Chantodo’s Resolve could also be better worded, especially when it comes to the AS damage scaling portion. Explaining more fully via the tooltip could help make it clear. As reference, this post from TinneOnnMuin:
I’ve got it.
The problem here is that you took two damage components, both of which could have the same APS scalar modifier. So they cancelled out. E.g. if the APS modifier is 1/2*APS, or let’s say 4/7*APS (see below…), then
4931992 / (2098227 / (1.4 * 1.07 * (1 + 0.42)*4/7)) = 2.857 = 5*4/7
On related note, I sat down did some controlled testing, and it looks like there is 4/7 hidden modifier on the APS scalar. Unless I missed a multiplier somewhere, but the number I got is 4/7 = 1/1.75 to 6 decimal places so I don’t think that’s a coincidence.
Conveniently, Chantodo’s wave always hits for exactly your average damage (no variance), so it’s way easier to test exactly than some other skills.
Test 1: higher APS
Attack speed = 1.4*1.07*(1+0.37+0.49) = 2.786
Int = 6200
Damage range = ((193+357)+(370+423))/2 = 671.5
Crit damage = 163
Additive = 10% (Magic Weapon)
Chantodo’s stacks = 1
Archon stacks = 49 (Fazula’s)
Archon multiplier = (1+49*0.06)*1.3 = 5.122 (Vyr4 so 6% per stack + Fazula’s stacks + base Archon damage buff)
Observed crits: 39,922,832
Expected crit: 1.4*1.07*(1+0.37+0.49)*(1+6200/100)*671.5*(1+163/100)*1.1*(1+49*0.06)*1.3*4000/100 = 69,864,945
39,922,832/69,864,945 = 0.571429 = 4/7 = 1/1.75
Test 2: lower APS
Attack speed = 1.4*(1+0.06) = 1.484
Int = 5711
Damage range = ((193+357)+(370+423))/2 = 671.5
Crit damage = 163
Additive = 10% (Magic Weapon)
Chantodo’s stacks = 1
Archon stacks = 0 (no Fazula’s)
Archon multiplier = (1+0*0.06)*1.3 = 1.3 (base Archon damage buff)
Observed crits: 4,977,881
Expected crit: 1.4*(1+0.06)*(1+5711/100)*671.5*(1+163/100)*1.1*1.3*4000/100 = 8,711,292
8,711,292/ 4,977,881 = 0.571429 = 4/7 = 1/1.75
So there appears to be a flat 4/7 = 1/1.75 scalar on the APS multiplier for Chantodo’s wave.
Went ahead and compared live to PTR (exact same build and setup). This is the exact scalar that popped out. Can confirm Tinne’s work! Thank you for jumping in, testing and explaining.
It seems like this is definitely not a bug then. This thread can be closed/disregarded. For anyone interested in a discussion regarding the feedback of this “hidden and unintuitive” nerf, you can participate in this thread in the feedback section: https://us.forums.blizzard.com/en/d3/t/chantodos-feedback-change-how-the-nerf-is-implemented/
Thanks for confirming. I was worried I missed something in the calculation somewhere, so I’m glad you got the same result. Gives me some piece of mind 
Nice work Tinne!
Guess I’m Saved from breaking out the spreadsheet. 
Consistent with the ‘feel’ of how much the nerf is. My estimate was 60%. Pretty close.
Thanks for testing all. 4/7 is reasonable nerf. About +0,5 GR could be fix squirt (only on average, not for max GR, with fishing max GR on live you fish for GR without frozen and with not bugged RG).
60% is -3GR. With fix squirt you are there.
To clarify for other readers, it’s ~3.5GR nerf. The ratio 1/1.75 is the key value there.
A downside to having it as a scaler value / ratio and not as lowered cap (as i would have expected) - other sets cannot take advantage of Chantodo’s as readily as Vyr.
Squirt’s bug fix will be nice yes. Thus far I’ve confirmed all of the below as fixed (perserving squirt’s through wizard shielding abilities):
Still need to test that man carver.
I have the following tested and “crossed-off”:
So far everything is fixed.
Sweet! Guess I’ve derailed the thread.
I will also test prides fall.
So sVr if there is a hidden 0.5714 Scalar reduction how much dps would we have to increase to offset said “nerf” if i can do GR 120 on live server in 9-13 minutes at paragon 3362 and sheet damage of 3.8 mil would i need 5.97 mil sheet (3.8 * 1.5714) to do the same? or is it 0.5714 per archon stack?
Neither.
You need 1/0.5714 times more DPS. That works out to 1.75x or 75% more damage. 3.8*1.75 = 6.65 mil sheet.