Heroes are characters at the game that give different statistics in different situations of the game.
Heroes are divided to groups, based on their rarity. Based on rarity is the colour and max level:
For upgrading the hero, you will need two components: relics and oaths. Relics can be obtained in hero shop and events, oaths can be obtained at daily rewards, events and at hero shop.
When the hero is fully upgraded, the relics that left are traded to Silver Stags. These you can exchange for hero relics in hero shop at the game.
You can add Heroes to a march or to a displayed council. The council is divided to 8 different seats:
Adding heroes to the seats of council, you add statistics, but only while the hero is at the seat. It’s better to assign heroes with similar statistics. You can also add the hero to a march. So, check all the statistics of the specific hero and upgrade the hero to desired level.