Boss Drop Rate

I actually disagree about passive skills hitting the boss affecting drop rate.

Looking at Magnus specifically -- without any interference I can get all 5 capes/shoes 100% with just my drop gear and no card or event.
I've had Xenon's loot for me, with their missles doing some damage (<0.1% hp) and still get all the drops. However, I've had Terebii; (paladin) loot before where he would attack. I was on a 2x card at the time, as well as all my gear (gear includes wolf), and only got 2 shoes and 3 capes. I believe there is a threshold damage that needs to be dealt for that individual to be included in the drop rate calculation.

This method of party drop rates has been around for as long as I can remember. Back when I killed Empress for weapons (when no one else in the server could), I noticed more drops when we both bought 2x cards.

I believe it has to do with who deals the killing blow, but I'm not sure. At least it seemed that way on my tests.