Grounds of Valor Prowess Questions

Increased Treasure Casket Discovery, Increased Crystal Yield and Treasure Hunter Bonus

I'm Wondering (mostly for treasure caskets but the others apply as well) is it the person that gets the kill shot or just does an action to the monster since when you finish a page everyone gets different rewards.

If its just an action does the effect stack say I have level 1 prowess and someone else has level 3 will that be level 4?
Seems like max casket level is 5 if we both have 5 will it be 10 or is that cap set to 5 combined?

Have a feeling only SE knows the answer for sure. I would like to know I am sure others would also, yes?

Guess Ill bump this at least once got pushed off the 1st page in like 5 mins of making it @ 1am so many probably missed it. Like or comment maybe we can get this answered.

I have done a lot of intense chest farm sessions. And just from my own experiences, i can positively tell you that it is only effected by the killing blows prowess. Good luck to you.

I also have some prowesses above lvl 10 at lvl 11 and beyond. 10 is not max by the way.

Also the prowess is not stackable among party members. Whoever has better casket discovery/TH/whatever prowess you desire, make them get the killing blow.