Heroes' Rarity is a classification of heroes that helps to determine which of them are stronger, more challenging to collect, and more valuable.
There are 3 types of rarity in the game:
  • Rare
Rare heroes are usually easier to farm, as their herostones are scatterred across many places in the game. Rare heroes can make a great team that will help you advance in the beginning of your journey.
If you want to know  which heroes are Rare, open the "Heroes" tab in the upper left corner, then tap Rarity.
Rare heroes' names are written in blue, and have blue flag with 'R' sign next to their names. You can find them in the Shops, by opening Crystals,  in the Campaign mode, Tournaments, Events and Quests.
  • Epic
    Epic heroes are a little more challenging to obtain, yet they are stronger and more valuable than Rare heroes. You will come across them later as you proceed through the game. Their names are colored in purple, and there is a purple flag with letter E next to them. You can find them in the Shops, by opening Crystals, in the Campaign modes, Events, Tournaments, and as a reward in other game modes.
  • Legendary  
    Legendary heroes are the most desired heroes, and also the hardest ones to find and collect. They will be a great addition to your collection, and will take your teams to the next level, granting you more victories and rewards on your journey.
    Their heroestones can be found in Personal Legendary Events, in competitive game modes, such as Tournament, Arena, Battlegrounds, Shops and other places in the game - stay on the lookout for the Legendary herostones. You can also obrain and summon them by opening Legendary and Epic Summon Crystals. Check where specific herostones can be collected in the following sheet : ALL_CHAMPION_LOCATIONS.png (2000×2000) (discordapp.com)