Shop RNG

Some games, you get offered the champions you need to build one or more champs up to 3 stars. Other games, you don't. But, the worst is when the game offers you 2 copies of each of your 2 star champions, but never a 3rd, and you can only fit 4 pairs and 1 single copy of the champions you're trying to collect. Then, the shop taunts you by offering lots of copies of the champions you don't already have 2 of, so you either watch champions you want to collect go by one after another without being able to buy them, or strategically switch only to see the 3rd copy of the champion you just sold come up in the next offering. To call this an exercise in frustration would be to put it mildly.

To prevent this, and to make success less arbitrary and capricious in general, I suggest rigging the shop to always offer 1-2 champion(s) with each offering that can help you progress toward upgrading, and 3-4 random other champions to let you diversify your team. Also, if you pay for a reroll, rig the results to not contain any champions you chose not to buy earlier in the same turn.