Quote Originally Posted by Physiologic View Post
You can also receive platinum for free by completing tapping the GET FREE PLATINUM link in your character selection screen (near the top). If you're on an iOS device it's entirely possible to finish enough offers to get every single campaign without spending any cash whatsoever.
Problem is, I'm on an Android phone, so no free plat for me. (Ran into the same issue with WarBucks for Gun Bros)