Board Thread:Wiki Discussions/@comment-79.183.132.105-20131208213553/@comment-129.255.231.184-20131211171940

What you have to remember is that opening the chests is basically like stopping a random number generator. Even if the percent chance is 5% (let's just say for arguments sake), each chest is an individual event. So opening 100 chests doesn't guarantee 5 epics, because each chest has equal probability of being an epic and each instance is not dependent on the last.

I know people get frustrated by this aspect of the game, but you also have to remember that for the makers of this game it is a source of revenue. So of course it is going to be a low probability of epics. If it was too easy no one would buy gems.