Experience

Expierience

 * Known as "King Level" this indicates the level of your towers and castles
 * You earn more expierience by upgrading cards and donating cards

What does this mean?

 * The more expierience (or XP) that you have the harder the opponent you logically have a chance to beat.
 * Keep in mind that this level does not unlock anything, it solely determines the HP and Damage of your King's Castle and Arena Towers
 * XP Gained from upgrades are listed on the card at time of upgrade
 * XP gained from donations vary based on the card type donated, i.e. Rare is worth 5 and Common is worth 1