Also D Major (Ionian), E Dorian
C# Locrian: C# D E F# G A B. Formula 1 ♭2 ♭3 4 ♭5 ♭6 ♭7. Same notes as D Major (Ionian), E Dorian, F# Phrygian. The darkest mode, with a flat 2nd and a flat 5th: its tonic chord is diminished, so it rarely feels at rest. It fits over half-diminished chords.