While the last Injustice glitch was patched with the 2.5 update, there is now a new glitch that, dare I say, is even better. This glitch allows you to sell any card you have an unlimited amount of times. The best part is, this works for both iOS and Android. Below are the steps.
1. Navigate to the "Sell" tab and go to the screen of the card you want to sell. Make note of the different tabs above labeled characters, support cards and skill cards- you will need to know where they are.
2. For iOS, double click your home button. For Android, turn off your device.
3. For iOS, go back in to the app, For Android turn on your device and go back in to the app
4. Quickly double tap on the card you want to sell.
5. Quickly click on a different tab than the one you're on (ex. if you're on characters, go to support cards)
6. When the pop-up to sell your cards comes up, make sure that it the background you are on the tab that you clicked in step 5. If not, re-do the trick.
7. If you are on the tab you clicked in step 5, you can safely sell the card. If you check back to the sell screen, you will see that you still have the card.
The money you earn with this glitch MUST be spent before you close the game. Once you close the game, all of the money will be gone. If you spend the money and close the game, the money will be gone, but you will retain the items you purchased.
If you have any questions about this glitch, make sure to ask. I'll be making a video on this soon for those of you who need to see the steps visually.