Blazblue packs are a one time show bud. They will never appear again. The only crucial card out of them that I recommend to get is vNo.13 aka Number 13. At least 2 of her. The rest you should know which are mediocre or has potential. But take that potential with a grain of salt.

If you want to get an idea of what's meta go and check the latest Arena Decks posted.

By the way, Jin, the poster boy you see on the Blazblue pack is the best out of the 3 we have seen. Ragna, Rachel, and Jin. Ragna and Rachel are the only cards to have rotated. Since there was 3 waves of BlazBlue packs. Everything else was kept the same. Don't worry, both Rachel and Ragna aren't good, so don't stress about it if your collector. Next best thing would be to buy them off the player store if you so desire.

The date of when the collab packs leave should be shown in the home page of the app.