To obtain and level up, characters purchase character packs in the shop. A free pack is offered every 6 hours.
Each character pack will randomly draw experience points (XP) for your current characters with a chance to award you a new character you don't already have! Once you've collected enough XP to reach the next level with your character, your character will level up and the bonus provided increases.
The amount of XP needed to reach the next level increases each time your chararcter levels up.
The total XP needed will be the next character level multiplied by 10.
Peter is level 4 trying to reach level 5.
5 x 10 = 50
A total of 50 XP is needed to reach level 5.