Dear Crows, let me give you a quick overview on the MUSIC Domain of Crowfall and which Major and Minor Disciplines they give you access to. If you want to check out what each Specialization Class brings to the table check out my Races and Classes Guide.
CREDIT: I want to thank Tinnis, who made an invaluable contribution by providing the descriptions of the disciplines I could copy paste as captions to you can search the disciplines and their abilities.
MUSIC DOMAIN DISCIPLINES
Bringer Of Life • fountain of life (ground target area: healing)• purify (removes group blackmantle, frostbite, pulsing damage aura and disease) 
Commander • hunker down (field increase damage; resist all)• courage (passive: increases lifesteal when a barrier placed on you.) 
Elementalist • neutralize elements (remove group burning, frostbite, electrocution and poison)• sentinel (increase critical chance when standing still) 
Entertainer • bolstering ballad (passive: increase group max health when singing)• reprise (passive: increase song radius) 
Gapfinder between the seams (buff: increase group piercing penetration)pin cushion (barrier negates piercing damage) 
Heavy Hitter • reverberating blow (attack: target enemey pulses damaging aura)• overwhelming odds (passive: gain resistance when enemies near) 
Minstrel • verses of victory (song: increase group attack, support power)• hymn of restoration (song: increase group health regen)• song twisting (passive: twisting songs increases song potency) 
Troubadour • requiem (song: increase enemy damage taken)• consonant chains (song: damage: snare enemies)• song twisting (passive: twisting songs increases song potency) 
Careless Whisper • careless whisper (passive: basic attacks buff crit stats) 
Dirge Of Dissonance • dirge of dissonance (song: damge enemies) 
Glamour Weapon • glamour (increase attack power) 
Guardian Rhythms • guardian rhythms (song: increase group mitigation) 
Heads Up • heads up (group increase perception; remove expose) 
Lament Of Sadness • lament of sadness (song: reduce enemy attack, support power) 
Last Resort • last resort (passive: gain crit chance on low health) 
Minor Accompaniment • minor accompaniment (passive: increase song damage) 
Phantom Armor • phantom armor (passive: chance to gain armor class when hit) 
Pound Of Flesh • pound of flesh (passive: damge bonus versus high health) 
Restoration Strike • restoration strike (attack: combo restores resource) 
Song Of Speed • song of speed (song: increase group movement speed) 
Toughness • toughness (group increase maximum health)