You can level up the characters to amplify their stats, and if you followed what we mentioned in our game guide you will know exactly how to pick the right stats (hint: always accept the stats if it's purple, else watch ads to reset and hope that you get it). You can also use the "Speed Growth" tab (under Fatima - AI tab) and once you head on there, you can tap on the EXP Packs to use them. You can see how many EXP Packs you own under each EXP Pack. These are good to level up your new Fatima when you get them.