Penetration

Does anyone know if you can give anyone negative protection?

lets say you are up against a Loki without Voidblade at lvl 20 (69 physical protection by my math), and you got Warrior Tabi, The Executioner, Jotun's Wrath and Voidblade (witch is 70 flat penetration with 3 stacks of executioner). Would that make Loki have 0 or -1 protection for you?

I would guess it only goes down to 0, but if anyone got a link or something to clarify it for me that would be great (only got my mac with me so can't check it out myself).

What we figured out after testing it out:

The Executioner: Is a debuff which reduces the targets protection by 5 + 7% of the targets max protection (before debuffs etc) per stack.
Voidblade: Is a aura debuff which reduces the targets protection by 15 (after the patch when tier 3 was split into two).
Titan's Bane: Is a percentage penetration which reduces the targets protection by 33% (after debuffs).
Warrior Tabi, Jotunn's Wrath and Focused Voidblade: Is flat penetration items, which is subtracted from the targets protection (after debuffs and percentage penetration).

So lets say we got every penetration item (Focused Voidblade) you can get vs a good with no protection except the natural protection (no protection items):
Protection numbers
Penetration numbers

A Poseidon would have 8 + (20*2.2) = 52 protection at lvl 20.

First we do the debuff stacks from The Executioner.
First stack 52*7/100=3,64+5=8,64. Second stack 8,64*2=17,28. Third stak 8,64*3=25,92.

Then we got Poseidon down to 26,08 protection with the 3 stacks up.

( Voidblade aura would put him down to 11,08 protection).

Then its down to the Titan's Bane (lets say we didn't have the aura from Voidblade).
The percentage will be 26,08*33/100=8,61

Then we got Poseidon down to 17,47 protection with the 3 stacks up.

And last, but not least we are down to the flat penetration.
Warrior Tabi, Jotunn's Wrath and Focused Voidblade puts the flat penetration up to 15+15+25=55 flat penetration.

Then we got Poseidon down to -37,53 (0 is the cap) protection with the 3 stacks up.

Your total penetration will be 25,92+8,61+55=89,53

Then the damage would be like this (lets say your base damage is 300):
300x100/(100+52-89,53 (52 because the cap is 0))=300 damage.

I tested out the negative protection myself, and I found out that the cap was 0 (Loki lvl 1 with 100 physical power and 40 penetration did 100 damage to Isis lvl 1 with no extra protection).

Hopefully my math is right now, would be hilarious if I manage to screw it up again xD

correct me if im wrong but it isn't the same to apply 21% + 15 penetration debuff from executioner at once than applying it by stacks of 7% + 5, the results are a little different, unless im missing something and the game just applies the next stack of that debuff from the total defense which is 52 and not from 43,36 after the first stack and so on which would result in a total of 27,85 after all 3 stacks are applied instead of 25,92 and also the flat penetration is capped to 50 right? so that would mean the total penetration from your previous calculation should be 84,53 instead of 89,53 if we follow your formula.

I tried your situation in a practice joust. With 3 stacks on executioner I did 317 damage to Loki. Adding a Titan's Bane boosted it to 362 with 3 stacks on executioner. It seems like it can go negative.

Situation without Bane
With Bane

So from what I understand! If I was guan yu and I had max 50 flat pen from warrior tabi, johtuns and focused voidblade. And then built titans bane, with all this combined with the max 30 pen debuff from his toulu assault the pen would be applied like...

30 debuff from toulu > 33% titans bane > the 50 flat pen = an anal hemmoraging amount of penetration and has a good chance of making enemies go into negative protections?