I've never gotten into trading/collectible card games such as Magic: The Gathering, etc., but many of the CCG gameplay aspects have found their way into various video games over the years, so I've had some exposure to some of the concepts.
One of the concepts found in CCGs is the idea of certain cards being much more common than others. Some of the terms I'm used to seeing in the videogaming world to refer to the different tiers of rarity are Common, Uncommon, Rare, Legendary, etc. This is pretty easy or arbitrary in video games where there's just some RNG and other RPG-esque stats which affect your chances of getting higher rarity items, but that brings me to the next half of the relevant aspects I'm interested in.
Another concept in CCGs is that building a good deck is often a small form of gambling; you have to buy a booster pack which contains, say, 5 cards, and you won't know what they are until you buy and open the pack. (AKA Loot boxes in video games.)
So essentially you end up with a bunch of "junk" Common cards that don't do a lot on their own, and very rarely get a Legendary card that is very good/powerful in the game.
My question is, how do these CCG companies decide what the proper ratio of each tier of card is to the others when printing and selling booster packs? Or in other words, how do they balance the frequency of obtaining the common, low-utility cards with the ultra-rare, high-utility cards, (and everything in between) so that people get just enough good stuff often enough to keep wanting more booster packs?
Does anyone who has any experience with these types of system have any knowledge on the subject, or know of any resources they could point me to that will explain some of these things?
To be clear: I'm not asking because I'm interested in creating some kind of "Free to Play" (Pay to Win) game with exploitative loot crate IAPs that milk thousands of dollars from "whales" who buy into that kind of thing. But rather my intention here is that it seems that the concepts of different rarity levels/proportions and (unpaid) "booster packs" could be used as a fun way to progress in a video game. But so far the only examples of these concepts I've seen involve IAPs (because they lend themselves well to it). So I'm curious if there's something about how the rarity and booster packs are designed fundamentally that require money/IAPs or if you could strip the money away from it and still have it be a fun, rewarding experience for the players.
I also kind of feel like I'm not doing a very good job of putting these thoughts into words. I'll blame that on it being 4 AM and this whole thought process kind of being one of those late night crazy ideas that my brain just can't let go of and let me sleep until I do something about it. So feel free to ask for more clarification if you need it.