This is still work in progress so hold on.
Ok Test was made on Glasscannon engi:
Armor Reduction through WS 44,7%
I needed to reduce one Conqueror Item to not have the BS buff to make errors in the testing.
So my real WS is 666.
Ok first Test was made vs CW Bloodletters in front of the WC.
With the AP activated the total mitigation was reduced everytime by 7.4%
So I guess my high WS left not much more room for the AP to reduce even more.
Although the Turret Armor Debuff got even some more out of it. I actually don't know how?
If the target was on 0% Armor then the debuff shouldn't even get more out of it.
Anyway that was vs NPCs.
Test 2 was vs a lvl 37 BO SnB
Mitigation 93,10% (Capped at 75%)
That are the Yellow Numbers.
The AP Buff reduced his overall Mitigation by 15.8%
BUTT the turret Debuff didn't changed that. We tested that for 3 times. All with the same result.
Mechanic wise it even makes sense. Turret reduces Armor of the Target. If the Target has still enough Armor to be above 75% it doesn't change the overal numbers.
Vs low Armor Targets the AP Buff gives a Glasscannon Engi something like 2-7% reduced mittigation.
Vs a 75% border Tank you get 15%, which can be pushed further by the Gun Turret Debuff to 19%
Vs a full deftard Tank you get 15%, which can't be pushed further by the Gun Turret Debuff.
Well that are the numbers I collected yesterday
It doesn't seem to be a simple 44.7% from WS plus 25% from buff. I don't know the formula behind it, but I guess the Toughness kicks in harder if more comes through the Armor.
I was told to use the AP Buff vs a "Real" deftard Dok with 4000 Armor. There the tooltip armor reduction of 25% should be achievable.