Jhin vs Swain

Save your 4th shot to trade: Whisper (passive) always makes it a critical strike with bonus damage, and each crit gives you move speed.

Fire Deadly Flourish (W) right after you or an ally hit the target: they're then rooted, and you gain move speed.

Place Captive Audience (E) in brush and along your escape path: the trap is invisible, slows the enemy who steps on it, then explodes.

Save the 4th shot of Curtain Call (R) to finish someone off: each bullet slows and hits harder on a wounded target, and the 4th is a critical strike.

Get out of the Nevermove (E) path as it comes back: it only roots on its return to Swain, then he can pull each rooted champion to him.

Leave the area as soon as Vision of Empire (W) appears: it strikes and slows 1.5 seconds later, and each champion hit gives him a Soul Fragment.

During Demonic Ascension (R), back off and hit from range if you can: he only drains nearby enemies, and his form ends when he stops draining.

If you have Grievous Wounds, apply it during Demonic Ascension (R): the drain heals him every second, and that healing keeps him alive.