What about adding an achievement for the bosses? Like a Lvl 20 for the ones that only go to ten and a 75 lvl achievement for the ones that go to fifty? I have seen some bosses that are near level hundred just being shared for the drops. Possibly another achievement for thirty-five attacks against the World Bosses, the rewards for the higher end are around thirty. And most of the players I know sometimes have a hundred or more attacks against them.