Rift is written in the key of F♯ Dorian.
According to the Theorytab database, it is the 9th most popular key among Dorian keys and the 45th most popular among all keys. The F♯ Dorian scale is similar to the F♯ Minor scale except that its 6th note is a half step higher (D♯). Chord progressions in Dorian have a characteristic sound due to the major quality of the chord built on the 4th scale degree.
See the F♯ Dorian Cheat Sheet for popular chords, chord progressions, downloadable midi files and more!