Bans are unlocked after the following criteria is met for each arsenal type. Number of bans allowed can be calculated from the third column and the total number of items you have. It’s also worth noting that the minimum items is not a hard requirement and can be bypassed by not unlocking some number of arsenal at all. It’s just a trade-off between how many items you want vs. making it less likely for worse arsenal to spawn.

Here are also the count of medallions unlocked at the start and by each pack, which could be helpful for planning.