Viktor vs Sivir

Poke with Hextech Ray (E), fired in the direction you choose: it hits every enemy in its line, and its upgrade adds an aftershock in its wake.

After Siphon Power (Q), land an auto within 4 seconds: it deals bonus magic damage, and the spell's shield covers you during the trade.

Place Gravity Field (W) in your target's path, then fire Hextech Ray (E): the field slows them, and if they stay in it for 1.25 seconds, they're stunned.

Glorious Evolution (passive) upgrades a spell every 100 Hex Fragments: Hextech Ray (E) to poke and clear, Siphon Power (Q) to survive, Gravity Field (W) to slow.

Place Arcane Storm (R) on grouped enemies: it follows the champions it just damaged on its own, and you can recast it to move it.

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.