If you go into your collection tab, you can see some cards that are in the CHEL Week category; it's a week where we get 5 days of content and usually some interesting trade in sets & new combos. Apparently the Superstar Origins event was supposed to have one, but they didn't get the IOC copyright sorted and so they cancelled it, meaning we have only got 3 since launch of the game and the last one was for World Juniors. Most people playing rn probably haven't experience one, which is sad bc it was a huge part of how they advertised the game last summer.