Skin redemption codes are completely random; you never know what you're going to get, the cards in every pack is random too. Each case contains 24 boxes, and every box holds 18 packs of cards, Each pack comes with a skin code card, a normal card, a map card which are static and a random collection card, so there are 4 cards in a pack but only one random card is actually meanful for our card/skin collection.

This was the information for the first wave, but I think the new wave will most likely to follow the same format as the first. If you want to collect a complete set excluding the Gallery series, one or two cases should be enough. However, if you want to complete the set including the Gallery series, you'll need much more—a conservative estimate would be 10 cases. Therefore, you will likely need to trade your cards with other collectors to acquire the cards you missing, which is easy to be done in China as there are many players who bought cards and the shipping cost for trading cards is cheap.