Ezreal vs Zeri

Land Mystic Shot (Q) as often as you can: each hit lowers all your cooldowns and adds a Rising Spell Force (passive) stack.

Detonate Essence Flux (W) with a spell rather than an auto: the orb deals its damage either way, but a spell refunds its mana cost plus a bonus.

Save Arcane Shift (E) to escape unless the kill is certain: it's your only way to reposition, on a 26 to 14 second cooldown.

Cast Trueshot Barrage (R) across the map to finish a fleeing target: it hits everything in its line, but deals less to minions and non-epic monsters.

Keep minions between you and her: Burst Fire (Q) stops on the first enemy hit, except during Spark Surge (E), when it pierces through them.

Don't fight near a wall against her: if Ultrashock Laser (W) hits it, it becomes an area laser that slows and critically strikes.

If you can engage, go in right after Spark Surge (E): it's her only dash, and each of her hits lowers its cooldown, so don't wait.

During Lightning Crash (R), back off out of her range: each hit she lands on a champion extends the effect and makes her faster.