Fire Emblem Engage centers on 12 Emblem Rings.
In the story, these magical rings were created during an ancient war and granted their bearers the power to summon or fight alongside legendary heroes from earlier Fire Emblem games. The rings were scattered across Elyos and divided among its kingdoms, forcing Alear and their allies to recover them during the campaign.
The rings are also the foundation of Engage's signature gameplay system. Equipping one gives a character new abilities, stat bonuses, weapon proficiencies, and inherited skills connected to its associated Emblem. A unit can then use the Engage command to fuse with that hero temporarily, gaining stronger attacks and a special Engage action.
The 12 main rings are associated with figures such as Marth, Celica, Sigurd, Ike, Lyn, Lucina, Corrin, and Byleth. They should not be confused with Bond Rings, which are weaker optional items that provide smaller bonuses and are generated from pairs of characters. Downloadable content adds Emblem Bracelets, but those do not change the original story's central count of 12 rings.