Heroes need to be summoned in order to use them. Some can be received in the Gauntlet, 1st purchase event (when using money for the 1st time), Gift-In event, randomly in the Springs (Cupid's and Aphrodite's), and even sent to your Mailbox. Alternately, they can be summoned by collecting their shards. Once summoned, Heroes have a have a signature quote and start out Level 1 with white rarity with no items, EXP, or skill points.
Summoned at 10 ShardsEdit
Summoned at 30 ShardsEdit