If you're talking about what damage is required to get a chest on each clan boss you can just click on the rewards in the clan boss tab and check 

I don't want to say that. I mean, how many damage is required to boss on hard mode for example? 6M,10M? And for every boss. Salute. 

Required for what? To get the top boss chest? To beat it? Your question is unclear, but if it is either of those options you can easily see them within the game.