Ezreal vs Vayne

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.

Don't stand with your back to a wall against her: Condemn (E) knocks you back, and if you hit terrain, you're stunned.

Take short, repeated trades: she's fragile, and on the third consecutive hit on you, Silver Bolts (W) adds true damage based on your max health.

During Final Hour (R), back off rather than risk your life: each champion she kills after damaging them extends the effect.