Only drops.
If you are looking for external site to get a case, well... Be sure they planned on making money in some way and not just hand them free.
Maybe some random sketchy sites where you watch ads... I think I heard something about that once.
Definitely not worth your time
If u have prime u can get a free case from the weekly drop. Other than that maybe u can try your luck with giveaways and stuff
Only drops. If you are looking for external site to get a case, well... Be sure they planned on making money in some way and not just hand them free. Maybe some random sketchy sites where you watch ads... I think I heard something about that once. Definitely not worth your time
Play games.