You don't have to be active in the EB or help at all, you just must be in the clan. The bonus only stays while you're in that current clan.
Maybe it's just because my app is refusing to update then. I haven't joined any other ebs in my clan but I know they've finished them
*city of the dead instead of call of the dead...probably already pointed out but I wanted to make sure u knew
Awesome thread. Not sure about the bonus from FoD though. It's the only one my clan hasn't finished and we have 8% to all. We are doing it now so I'll let u know how much it increases if we finish.