Think Nirvalen

Think Nirvalen (シンク・ニルヴァレン, Shinku Niruvaren) was an Elf that lived during the Great War. She is Fiel Nirvalen's ancestor. She is the creator of the Spirit-Breaking Rites, including Void Zero Protection and Eternal Fourth Protection. Riku Dola paid her a visit as part of his plans to end the war.

(Source: No Game No Life Wiki)