Experience for heroes is gained by Enhancing heroes, meaning other heroes are sacrificed.
The costs of enhancing is 120 coins per level and per hero.
Common low level heroes are usually not worth the cost. Rare high level heroes, however, will also have a significant impact. Moreover, high level heroes with the same AP Skill, give a chance of increasing the AP Skill level.
Suppose we want to enhance a hero at level 50 while sacrificing 5 other heroes.
Then the cost is 50 x 120 x 5 = 30,000 coins.
Effect of Sacrificing heroes Edit
1) Material cost increases per level.
2) Each hero has their own xp value when used as enhancement materials.
3) The xp value of the material appears to be multiplied by the material's level.
4) Special materials, like EVO and COIN, seem to be unaffected by other influencing factors mentions below.
5) When sacrificing heroes of the same element as the hero to enhance, the xp value per herois increased by ~20% with the decimal values included when using multiple heroes.
6) The integer value seems to used after all 1-5 material xp values (including decimals) are combined and multiplied by the success factor.
7) The number of additional heroes sacrified beyond one (2-5) per enhancement influences the final result to an unknown degree. This only applies when the materials and the hero are the same element.
8) The displayed xp gain when using multiple heroes may not be the actual xp gain.
9) The success results appear to be +50% for Great Success and x2 for Super Success.
AP Skill Levels Edit
Enhancing a hero with the same AP skill as the hero sacrificed gives you a chance that the hero will gain an extra AP Skill level. If many heroes with the same AP skill are sacrificed at once, it is possible to gain more than one extra AP Skill level. This table can be used to find heroes which have identical AP skills.
An extra AP Skill level has the effect of lowering the AP cost of the associated skill by 1 point.
The game makes it clear that this is possible by showing a blinking "skill" icon in red on top of the hero.
The AP skill level of a hero is lost when evolving.
The AP skill level can still be increased if the Hero has already reached his regular maximum level.
See also Edit
See the Table of Hero Experience for the amounts of XP necessary to level up heroes.