Caitlyn
Time for a Shakedown
Lane harassment and consistent damage output.
Resolve
Durability and crowd control
Grasp of the UndyingEvery 4s your next attack on a champion deals bonus magic damage, heals you, and permanently increases your health.
DemolishCharge up a powerful attack against a tower while near it.
Bone PlatingAfter taking damage from an enemy champion, the next 3 spells or attacks you receive from them deal 30-60 (based on level) less damage.
Duration: 1.5s
Cooldown: 55s
OvergrowthGain permanent max health when minions or monsters die near you.
Precision
Improved attacks and sustained damage
Legend: AlacrityTakedowns on enemies grant permanent Attack Speed.
Coup de GraceDeal more damage to low health enemy champions.
Adaptive Force
+9
Adaptive Force Adaptive Force
+9
Adaptive Force 
Health Scaling
+10-180 Health (based on level)
Why Grasp of the Undying
Grasp on Caitlyn allows you to constantly harass in lane for a bit of extra damage as well as a small amount of lane healing sustain.
Why Demolish
Demolish on Caitlyn is great for punishing lanes where you are able to keep pushed for early tower plating gold.
Why Bone Plating
Bone Plating on ADCs is huge to helping you survive early burst damage, especially when paired with the extra HP from Grasp.
Why Overgrowth
Overgrowth's bonus HP scaling is synergizes well with the extra health from Grasp to help you survive early damage and scale to a point where you're able to get 3+ items.
WhyLegend: Alacrity
Attack Speed is arguably the most important stat on Caitlyn as it will help you get more passive headshot attacks off as well as make Grasp procs easier to use.
WhyCoup de Grace
Coup De Grace's damage amp is a staple for any marksmen's mid-to-late game damage arsenal.
All About Them Headshots
Lane harassment and consistent damage output.
Precision
Improved attacks and sustained damage
Fleet FootworkAttacking and moving builds Energy stacks. At 100 stacks, your next attack heals you and grants increased
MS .
Absorb LifeKilling a target heals you.
Legend: BloodlineTakedowns on enemies grant permanent Life Steal, up to a cap. Once the cap is reached, increase your max health. Weaker earlier but stronger later game than other Legend Runes.- Coup de Grace
Deal more damage to low health enemy champions.
Sorcery
Empowered abilities and resource manipulation
Absolute FocusWhile above 70% health, gain extra
adaptive damage .
Gathering StormGain increasing amounts of AD or AP,
adaptive over the course of the game.
Adaptive Force
+9
Adaptive Force Adaptive Force
+9
Adaptive Force Health Scaling
+10-180 Health (based on level)
Why Fleet Footwork
Fleet Footwork on Caitlyn empowers your ability to take trades early and often in the laning phase thanks to your improved sustain. The extra burst of Movement Speed can also help you position to get in range for the headshot proc on the enemy.
Why Absorb Life
Overheal's poke resistant shield its great for establishing lane dominance with your long auto attack range to mitigate incoming minion damage.
Why Legend: Bloodline
Bloodline further empowers your ability to take lane trades and out sustain your enemy laner thanks to Fleet Footwork and Bloodline's extra bit of healing.
Why Coup de Grace
Headshots paired with the execute damage of Coup De Grace offers you a lot of burst to finish off your target and move on.
WhyAbsolute Focus
The extra AD granted form Absolute Focus allows you to sit in the backline and dish out massive amounts of damage once you have built a few crit items.
WhyGathering Storm
Gathering Storm is your late game insurance policy for damage. If you fall behind, try stalling out the game by denying their tower siege with your Traps. The longer the game goes the better shot you have of coming back with Gathering Storm.