Heroes gain levels while you play games with them. The amount of XP gained is equal to amount of gained in the game, plus 50% if you have alternate outfit bought for the hero. You can also gain XP if you select an already max upgraded card from the pack (as listed here). Each level gained rewards a 250 bonus, and certain levels will unlock/upgrade that Hero's card: The card is unlocked at level 4, upgraded at level 8, and max upgraded at level 28. Please note that while getting hero level 8 (and thus 2nd level hero card) can be done in a single day with some effort, getting hero level 28 is a tedious and time consuming task, possibly requiring weeks or even months of playing, due to the way XP required for level is set.
XP required to level up from level is equal to 1.2 * XP required for level , which makes it growing exponentially quite fast. The exact formula is:
The actual values used in-game are presented below for your convenience, up to level 30. The levels that you unlock/upgrade hero card are bolded (4, 8, 28). Note that the total amount of experience required for level 28 is about twice the total amount required for level 24, i.e. it takes about the same amount of play time to level from 24 to 28 as to level from 1 to 24.
|Hero Level||Total XP||XP to level up|