You can hire Allies to help you in Boss Fights and War. Allies will be alerted on their News page when you ask for help on Boss Fights. Allies will also allow you to bring more items into War helping your defeat your enemies. You can hire Allies by sending them a request and some cash. If they accept the request, they will become your Ally. If you want to add your friend as an Ally, ask for their Army Code or give them yours. Then they will be able to add you as an Ally for free.