Sona uses the stance mechanic. Her basic abilities all have a persistent aura effect which remains for as long as she doesn't activate another ability. Additionally, her auras remain for 1 additional second after changing stances. Each ability also has an activation effect upon being cast. Sona's basic abilities also set off a 0.5 second cooldown to the other two basic abilities.
Power Chord
After casting 3 spells, Sona's next attack deals extra 8 + (10 × level) magic damage. This enhanced attack has an additional effect depending on which spell was cast last.
Hymn of Valor
Cooldown: 7
Cost: 45 / 50 / 55 / 60 / 65 mana
Stance – Persistent Aura: Sona plays the Hymn of Valor, granting nearby allied champions bonus attack damage and ability power until she changes stances.
Stance – Persistent Aura: Sona plays the Aria of Perseverance, granting nearby allied champions bonus armor and magic resistance until she changes stances.
Armor & Magic Resist: 3 / 6 / 9 / 12 / 15
Aura Diameter: 2000
Activation: Sona sends out healing melodies, healing herself and the most-wounded nearby ally champion. Additionally, both Sona and the healed champion will receive additional armor and magic resist for 3 seconds.
Power Chord - Diminuendo: If this spell was last cast when Sona's Power Chord is ready, her next attack will debuff the target to deal 20% less damage for 4 seconds.
Stance – Persistent Aura: Sona plays the Song of Celerity, granting nearby allied champions bonus flat movement speed until she changes stances.
Movement Speed: 4 / 8 / 12 / 16 / 20
Aura Diameter: 2000
Activation: Sona energizes nearby allies with an additional burst of speed for 1.5 seconds.
Power Chord - Tempo: If this spell was last cast when Sona's Power Chord is ready, her next attack will slow the target by 40% for 2 seconds.
Bonus Movement Speed: 6% / 8% / 10% / 12% / 14%
Targeting Diameter: 2000
Crescendo
Range: 1000
Cooldown: 140 / 120 / 100
Cost: 100 / 150 / 200 mana
Active: Sona plays her ultimate chord in a broad line in front of her, forcing enemy champions caught to dance stunned for 1.5 seconds and take magic damage upon impact.
3150 or 
790
