Power stones dropping rate

Is it difficult to gather power stones to you guys too? For example, I only have 9 power stones and I'm already at lvl 67 in Dungeon. I haven't had a single power stone for a 10 levels and it gets more difficult to defet monsters. Bonus question: Does it happen to you that you defeat level in Dungeon with three stars and when you go in to play again, it shows the same level again?

I'm at 60 and i got 8 so yea they are hard to get. It happens all the time, it doesen't even give much xp all the time

And I need 50 of them to level up my dragon. Yeah, sureee!!! Maybe in couple of years :D

I'm at level 62 and I have only gotten one so I think its Luke a very rare drop