A "patched" or "unlocked" APK typically aims to provide a complete experience that might otherwise require significant time or real-world currency to achieve.
Since Magic 2015 is an older title, official support and server stability from Wizards of the Coast have dwindled. For many, a modded APK is the only way to enjoy the game's full features without encountering "Transaction Error" messages that often plague the official legacy version. Risks and Considerations magic 2015 apk mod unlock all patched