Garen vs Kennen

Trade with Decisive Strike (Q), then Judgment (E), and back off: the Decisive Strike silence stops your opponent from answering with spells.

During Judgment (E), stay closer to your opponent than to their minions: the nearest enemy takes extra damage.

After a trade, back off until Perseverance (passive) kicks in: without recent damage taken, you regenerate part of your health every second.

Activate Courage (W) just before the bulk of the damage: you first gain a shield and tenacity, then a longer damage reduction.

Save Demacian Justice (R) to finish: its true damage grows with the target's missing health.

Dodge Thundering Shuriken (Q): each spell that hits you applies Mark of the Storm (passive), and on the third, you're stunned.

Back off as soon as he rushes at you with Lightning Rush (E): it's his engage, often followed by Slicing Maelstrom (R).

When he has Slicing Maelstrom (R), spread out from your allies: the storm hits every enemy around him, and its repeated hits end up stunning.

Wait for Slicing Maelstrom (R) to end before you fight back: during the storm, he gains armor and magic resist, then the spell has a 120-second cooldown.