Ignore def doesn't stack

How about this?



Specifically, the 22k

Max Range is 20677, 6% Damage on my dagger makes that ~21918, Phantom ignores 20%, Katara has 15% Ignore, Book has 15% Ignore, 2.5% Ignore from Ambition.
Total DEF Ignore = 52.5%
Blue Snails have 10% PDR

So, (1-.525)*.1 = 0.0475 PDR, which means I do 95.25% of my damage.

Phantom does 105%

Max damage I should be able to do is 1.05*.9525*21918 = 21921

I have no idea it might just be certain skills that does not stack with ignore def or certain skills that replaces all ignore def % completely. It would seem however if ambition ignore def is subtractive that ss would make more sense, can you hit below your min dmg?