Laevatain

レーヴァテイン, Laevatein,Laevatein,Searing Steel

Laevatein is an antagonist from Fire Emblem Heroes. She is a princess from the Kingdom of Múspell, Surtr's daughter and Laegjarn's younger sister. She is seen fighting Alfonse in the opening cinematic.

(Source: Fire Emblem Wikia)