Crystal drop rates are supposed to set or random?

Jabbawokky

I was wondering if drop rates were set or random. Im asking because I watch the same people get 4* drops repeatedly week after week, and i have gone well over half a year without a phc drop. Why is it Im grinding just like them, opening just as many crystals, but going getting a single 4* every 9 or 10 months out of phc and shards, and they or getting on average 2 a week? I will hush now before i say something i shouldnt

Ghost_BlaZe

It's random. When I first started it took me 5 months to get my first 4*. And I've seen that they have increased the odds since the beginning but my last 20 premiums I've gotten maybe 2 3*s when it used to be 3 for every 10