You can summon heroes in the shop, capture heroes from dungeons, or find some from chests.

Rare summon gives you heroes of three to even six stars. The higher the star count, the rarer that hero is. Each day, there is an increased chance to get the hero that is highlighted in the shop. Rare summons require gems, which you can earn from quests or buy from the shop.

Honor summons will give you a random hero of one to three stars, or XP ghosts or evolve materials of one to five stars. Honor summons require honor, which you can obtain from friends.

You can also capture heroes from story mode. Each time you defeat an enemy, there is a chance it will be captured. The higher the star count, the rarer it is to capture that enemy. You can only capture one enemy per room, so you may want to target the enemy you wish to capture first for the best chance of capturing it. You must complete the dungeon to claim the heroes you captured in that dungeon. If you don't survive the dungeon, you will not capture any heroes.

Sometimes you receive heroes from chests too, though high-star heroes are very rare. You can obtain chests by completing dungeons if you have free chest slots, or you can purchase them from the shop with gems.