Sett vs Tryndamere

Start your trades with Knuckle Down (Q): you rush toward your target, and your next two autos deal bonus damage based on their max health.

Cast Haymaker (W) right after taking damage: the stored Grit gives you a shield and extra damage, dealt as true damage in the center of the punch.

Don't back too early at low health: Pit Grit (passive) increases your health regen based on your missing health.

Stand between two enemies before Facebreaker (E): grabbed from both sides, they're stunned, otherwise only slowed.

Grab their tank with The Show Stopper (R) and slam them onto their carries: the damage around the impact depends on the bonus health of the target you grab.

Avoid taking a trade when his Fury is high: with Battle Fury (passive), it raises his critical strike chance, and Bloodlust (Q) turns it into healing.

Hit him when he walks up to minions to farm: each last hit gives him Fury, which Bloodlust (Q) then turns into healing.

Against Mocking Shout (W), back off sideways rather than turning your back on him: the spell only slows enemies who are facing away from him.

Once he hits level 6, plan for what comes after Undying Rage (R): he can't die during the effect, so back off or hold any CC you have, and finish him when it ends.