After you do the first revival, you'll be able to get honor coins, which can be found in abundance inside of your inbox, or earned in the arena. Beyond that, keep enhancing your units, finding rarer ones and unlocking more slots so that you can dominate the battle realm. And make sure that you have at least five units and that they are of different elements. Before you go here, though, make sure to have spent some medals in enhancing your 3-5 star units (ignore the ones with less stars than that). The battle area is where you can compete against other players.