Sona vs Nami

Choose the spell you cast before Power Chord (passive): after Hymn of Valor (Q), the auto deals more damage, and after Aria of Perseverance (W), it weakens the target.

After each spell, move close to your allies: your aura gives them a damage, shield or speed bonus depending on the spell.

Hit champions with Hymn of Valor (Q) and shield allies with Aria of Perseverance (W): Power Chord (passive) gives you ability haste, then reduces the cooldown of Crescendo (R).

Save Crescendo (R) for when several enemies are in front of you: it stuns them all and deals damage to them.

Change direction when she casts Aqua Prison (Q), then step up if she misses: it's her only stun outside her ult, on a 12 to 8 second cooldown.

Avoid trading when she casts Tidecaller's Blessing (E) on her ally: their next autos and abilities slow you and deal more damage.

Step out to the side of Tidal Wave (R): it travels a long way but moves slowly, and its slow lasts longer the more distance it has covered.

If you can engage, target Nami when she steps up: with no dash or leap, she can only walk away.