No cap.  Active debuffs.

So Gnishak should be wearing 9 piece feral for sure now lol

Thanks!  

If you were using him in a PvE setting sure.  Riho best in class for Feral though.

Youre welcome.

But wouldn't the Dmg Boost from Riho apply only to the target with the Debuffs?

I figured the damage boost was calculated individually? 

Or is it calcualted by total debuffs out and then damage is boosted agaisnt all enemies?

I'm using it on Eostrid for Hydra and have seen good damage improvement in spite of the continued nerfs to champ damage.

It's just this in the Info section: "...allies deal 5% more damage for each active debuff cast by wearer"

So each debuff out there from your feral champ, your allies deal 5% more damage.