You can perform upgrades in your characters by tapping the Astrotrain at the bottom right of the map screen. Upgrades will improve your armor, weapons, and will increase the time you can spend as a vehicle. After choosing which character to upgrade, you can choose to upgrade that character in exchange for gems, or you can choose to use coins and crystals. Updating with coins and crystals takes longer, but when using gems, characters are upgraded immediately!
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