Directly to you from Twitter:
Get Ike: Vanguard Legend as a 5★ ally!— Nintendo of America (@NintendoAmerica) February 28, 2018
Ike: Vanguard Legend was the champion of the #FEHeroes A Hero Rises event. Clear Xenologue 3: The People's Hero under Story Maps, then Paralogues to obtain your 5★ ally! pic.twitter.com/dO2qK45y6d
…Wanna play? Buy a 3DS.
That being said, click on Fire Emblem Heroes for everything you need to know about the game. 😀