When your Hero reaches a new level, they receive Skill Points, which are required to upgrade the Hero’s Skills.
Upgrading the Hero’s Skills is instant and does not require resources or Gold.
The Hero’s Skills that are currently available for upgrade have brightly colored icons. Those which cannot be upgraded at the moment have gray icons.
Depending on the style of play you prefer, you can improve the stats you need by upgrading the corresponding Hero’s Skills.
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