I got the last piece this morning. I didn't buy the stash or spend any diamonds, but I did focus on getting all the 79 slots I could. I know that was not the way they said to go; they said to concentrate on 22 and 23 in order to get the furthest on the maps. But I just didn't see it that way, so I kept going for 79 or 75, first of all, because none of the prizes absolutely sucked (I'm looking at you, 10 broken shards and inspiring meditations) and because they offered the most cash return as one of the prizes. It worked ... I got the 200 cash back or the 150 cash back maybe once out of every 10, which propelled me forward. Of course, I won't hit gold league ... I'm convinced you can't get that without spending diamonds. But this is good enough for me.