Guardian Cross is developed by Square Enix who made the Final Fantasy series. The game was launched like 4 days ago for iOS only but there are plans to push out the game to Android soon.

It's a pretty similar game concept to Rage of Bahamut, which is an addictive card based game and it's also a free app. Take some time to try it out!

At the registration, you can use the following as the referral code which will give you a Rare or Limited Edition card to start off with.
Referral: TR64110

Cheers and have fun! Thanks!