FCE ToolBox has been completely updated for the revised exam. Each of the four sections of the app addresses one of the four Use of English Questions. Eight short videos explain the different types of Key Word Transformation (active to passive, result clauses, using 'although' and 'despite' etc), with a series of exercises provided for each topic.
It's free of charge to get the installer of FCE ToolBox, also, you can have a look at users' reviews on Droid Informer. The app works fine on Android 4.0.3 and higher. It's secure to download this application. VerbBusters has developed the tool that lies within the Educational category.