I have this as my coverphoto but shes a character from the Anime Kono Subarashii Sekai Ni Shukufuku Wo! (この素晴らしい世界に祝福を！)
Her explosion magic is pretty awesome! :)
Also, you can watch the anime for free here! ;)
https://www3.animepace.si/anime/kono-subarashii-sekai-ni-shukufuku-wo-