You must have Fire
Emblem Fates: Birthright or Fire
Emblem Fates: Conquest to access this content.

Two kingdoms have met at the crossroads of war, and you’ve walked the
path of loyalty or kinship. Yet some mysteries remain unsolved. After
purchasing either the Fire Emblem™ Fates: Birthright
version or the Fire Emblem Fates: Conquest version, take a leap
of faith in this third path by aligning with neither royal family. The
secrets you seek await you in another realm. Dare to discover the hidden
truth.

In this revelatory Fire Emblem™ experience, your customized
avatar is the main hero. An army of knights, mages, archers and more are
at your command for the most challenging battles in series history. Each
unit and weapon has strengths and weaknesses that you must balance
against the foes they face. Partner your allies on the battlefield so
they can support one another in combat. Building relationships is
key—the closer your allies become, the better they’ll fight together.

An epic storyline centered on the main character who is forced to
choose between his bloodline and the family who raised him

Play as either a male or female protagonist; this customized avatar is
the main character

New “My Castle” area to interact with your allies and build stronger
relationships

Have StreetPass™ encounters with other players to visit their My
Castle or battle against their armies to have the chance to recruit
them.

amiibo™ compatibility–scan the corresponding amiibo and Marth, Ike,
Lucina, and Robin will appear in your game for you to battle and
recruit. (amiibo sold separately. Compatibility and functionality of
amiibo may vary per game. Visit amiibo.com for specific details on how
each amiibo works.)

A series of DLC maps will be available for purchase, with new maps
releasing every week (from 2/19 – 4/21)