%boss dmg not working?

I'm beginning to think Demon Slash's reinforcement isn't working properly or is falsely advertised.
No matter what I put in, additive or multiplicative, none of the numbers match all your numbers on your Jr. Pepe kill, which isn't even a boss.
Additive:
380%, 380%, 370%, 370%.
Doesn't fit.

Multiplicative:
380%, 380%, 342%, 342%.
Doesn't fit.

Different type of multiplicative:
655%, 655%, 589%, 589%.
Doesn't fit.

Different type of multiplicative again:
280%, 280%, 252%, 252%.
Doesn't fit.

Before smartass replies.
I did account for his ignore PDR (30% from Dark Bind) and his 9% total damage.

There's another glitch but I don't think it's ever been posted on SP yet.

Dark binds 30% ignore effect only happens when it's used. Zak takes 800ks off bind and 900k-999k when bind is on it.

Unless it has a passive + active for 60% ignore def, but I'm pretty sure the ignore def only works when bind is used on the monster.