Viktor vs Xerath

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.

Keep minions between you and Xerath: Shocking Orb (E) stuns the first enemy hit, for longer the farther it has traveled.

Don't stand still, and change direction often: Arcanopulse (Q) hits a target moving forward or backward in a straight line much more easily.

If you can engage, go in while he charges Arcanopulse (Q): he slows down by up to 50%, and he has no dash to escape.

If you have CC and can reach him during Rite of the Arcane (R), use it: he channels the ult, and interrupting it stops his shots.