When Sona is worth a pick, when it is worth a ban, and what its kit commits your team to.
Locking Sona commits your team to a fight pattern: make somebody else win a lane, then convert map presence into objectives. A draft that cannot support that pattern does not improve because you play well.
550 attack range means Sona wins by not being where the fight is. Spacing is the whole skill, not a detail of it.

Accelerando: Sona gains non-Ultimate ability haste permanently for her basic abilities as she uses her abilities well, up to a cap. Beyond that cap, further successful uses reduce her ultimate's remaining cooldown instead. Power Chord: Every few spell casts, Sona's next attack will deal bonus magic damage in addition to an additional effect based on what basic Ability Sona last activated.
Sona plays the Hymn of Valor, sends out bolts of sound, dealing magic damage to two nearby enemies, prioritizing champions and monsters. Sona gains a temporary aura that grants allies tagged by the zone bonus damage on their next attack against enemies.
Sona plays the Aria of Perseverance, sending out protective melodies, healing Sona and a nearby wounded ally. Sona gains a temporary aura that grants allies tagged by the zone a temporary shield.
Sona plays the Song of Celerity, granting nearby allies bonus Move Speed. Sona gains a temporary aura that grants allied champions tagged by the zone bonus Move Speed.
Sona plays her ultimate chord, stunning enemy champions and forcing them to dance and dealing magic damage to them.
Difficulty 4 of 3, ranged, support. Those three facts decide how safe this is to pick first, and the melee ones are almost always the riskier blind.
Worth reading even when you are the one playing Sona: it is the list of what your opponent is being told to do to you.
Sona is Demacia's foremost virtuoso of the stringed etwahl, speaking only through her graceful chords and vibrant arias. This genteel manner has endeared her to the highborn, though others suspect her spellbinding melodies to actually emanate magic—a Demacian taboo. Silent to outsiders but somehow understood by close companions, Sona plucks her harmonies not only to soothe injured allies, but also to strike down unsuspecting enemies.
Full Sona page — abilities, stats and every skin →