This is an educational question rather than a current need. I wanted to try out the exercise of harmonising an Orthodox chant. I learn from St. Ikhon's to give the melody to the alto, soprano descant a third above, tenor a sixth below (or maybe I could try a fourth). They provide bass lines, and I am wondering what the conventions are for writing them? All my previous knowledge is based on common triadic harmonic practice, where the piece ends on the tonic. But that's not the case with (modal?) chant. (I seem to recall I might have asked about this topic before, but I'm still learning.) The key signature of the Cherubic Hymn may be F major or D minor, and a D minor drone would fit, but the St. Ikhon arrangements end with an octave unison on the melody Bb. And rather than following the same text homorhythmically, the bass line is slower. In other cases I see a bit more interest added just before a cadence. Are there recipes for how this is done? I know I could just use a Ledkovsky arrangement or similar but I'd like to know how this works. Thank you.