Board Thread:Question and Answer/@comment-70.70.29.204-20161017232109/@comment-29788570-20161022124959

To tell truth, it works the same way as cash boxes. the difference is just the rates, but probably isn't 1% for UR also, but lower.

And, just clarifying, as you keep summoning yeah the rate stays the same, but the probability of getting the UR rises. (Obviously, if there is 2 cards it's much easier to get the UR than at 300) But i understood what you meant

Basically N/R cards have a high rate, while SRs have lower, and UR extremely lower (comparating to others; Like the cash boxes), that's also why i think it's easier to get amalg version than pure UR version.