Seraphine vs Sivir

Make Surround Sound (W) your third basic spell: Stage Presence (passive) casts it twice, and the second, cast while shielded, heals your allies.

Cast Beat Drop (E) on enemies that are already slowed: they're rooted, and those already immobilized are stunned.

Save High Note (Q) for a wounded target: its damage grows with the health they've lost.

Cast Encore (R) through an ally toward the enemies: each champion hit, allies included, extends the spell's range.

Dodge Boomerang Blade (Q), then its return: it damages on the way out and on the way back, and it costs Sivir a lot of mana.

If you have CC, cast a cheap spell first, or fake a step forward: Spell Shield (E) only blocks one ability, and heals her if it blocks.

Back off when she casts On The Hunt (R): her whole nearby team gains move speed to engage on yours.

Don't leave her alone on a lane for too long: with Ricochet (W), her autos bounce between minions, and your wave, then your tower, fall fast.