Why can your guardians sometimes attack twice? This will help explain a little on how you can arrange your deck.
Credits to Whaz over here: http://guardiancross-forum.com/Thread-AGI-Formula-Explained
In summary, the system should be based on the Active Time Bar (ATB) from Final Fantasy games. The bar is 10, 000 agility points so your guardian's agility is added to it till the bar is full. Once a bar is filled up, the guardian attacks. If the guardian dies, the bar is carried over for the next guardian to continue filling up.
iTunes App Store link: Guardian Cross - SQUARE ENIX
