Kayn vs Lillia

Take Rhaast against a tanky team, Shadow Assassin against squishy targets: The Darkin Scythe (passive) gives one healing, the other bonus damage at the start of fights.

Gank through walls with Shadow Step (E): you move through terrain faster, and you heal when you first enter it.

To dodge a burst, cast Umbral Trespass (R) on a champion you just hit: inside, you're untargetable while your spells come back up.

As Rhaast, hit as many champions as you can with your spells: The Darkin Scythe (passive) heals you for part of the ability damage they take.

Against Blooming Blows (Q), stick to her or back out of range: only the outer edge of the zone adds true damage.

Get out of the center of Watch Out! Eep! (W): the zone deals much more damage there than at the edge.

Dodge her spells, even Swirlseed (E), which rolls to the first enemy: each one marks you for Lilting Lullaby (R), which puts every marked enemy to sleep.

If you have CC, use it on her: with no dash, she relies on the move speed Blooming Blows (Q) gives her for each spell that hits.