If you are playing on a mobile data plan, it may be important for you to know how much data playing the game will use. While usage may vary, on average data usage is <1k/second at the height of combat.
So 60K/ minute = ~3.5 megs/ hour.
Of course, your mileage may vary. We hope that helps you plan out your data usage. Where possible, play on Wifi so you don't have to worry about it.