Master Yi vs Zyra

Cast Alpha Strike (Q) to dodge a spell or a burst: you're untargetable during the strike, and your autos lower its cooldown.

Cast Meditate (W) to tank a burst mid-teamfight: you take less damage, heal more at low health, and the time left on Highlander (R) is paused.

Activate Highlander (R) to chase: you gain move speed and attack speed, and slows no longer affect you.

Chain kills in teamfights: each takedown lowers the remaining cooldown of your basic spells, and extends Highlander (R) if it's active.

Get out of the line of Grasping Roots (E): the roots pass through minions and root every enemy hit, then her plants hit the trapped target.

Step on her seeds to destroy them before she grows them: Rampant Growth (W) seeds reveal you for a moment, but leave her no plant.

Take down the plants born from Garden of Thorns (passive), or back off until they die: they take fixed damage, like a ward, and don't live long.

Get out of the Stranglethorns (R) zone as soon as it appears: the vines knock you into the air 2 seconds later, and her plants are empowered inside.

If you can engage, go for Zyra when her plants are far from her: the Thorn Spitter from Deadly Spines (Q) only fires at 575 range.