One-shot-one-kill. That is the way of the sniper. This build maximizes usage of Caitlyn's ultimate, utilizing 30% cooldown reduction with 3x items with 80 attack damage. The other 2 items give armor penetration and the much needed movement speed. This is not a close-range pushing build, although the attack speed and critical chance help autoattacking in lane. Evasion is the staple of the sniper, and being able to move around freely to snipe the **** out of enemies is a must. Starting with 325 movement speed, Caitlyn is one of the slowest and most unwieldy champions. Endgame, with good skill timing, you can even outrun master yi's Highlander. To use this build most effectively, hide in unwarded bushes and begin with Piltover Peacemaker or Ace-In-The-Hole while the enemy thinks they are dueling your teammate 1v1. You or your teammate must be good at timing and cleaning up kills to utilize this build effectively. Enjoy the build!

You may want to build Bloodthirster first, for strong laning potential with the lifesteal. This means you will save money on health pots for mana pots - to fuel your expensive abilities.

Alternatively, if you end up having to retreat first, you may want to choose Avarice Blade to help you gain money throughout the game. This means you will expect a longer and more conservative game. You may want to follow with a Bloodthirster.

After your first few purchases, you may want basic boots to temporarily increase your speed, because your speed is your survival!

Following Bloodthirster, follow up with Zephyr to increase your speed, reduce cooldowns, and give a little boost to attack damage. An added benefit to Zephyr is tenacity. Perhaps you accidentally step on Teemo's mushrooms. You will not be slowed for too long with Zephyr. =D

Afterwards, you can get Infinity Edge for a small chance to critically hit enemies, or you may want an Essence Reaver to reduce cooldowns further and have your 30% endgame bonus lifesteal. Essence Reaver also restores mana on hit, so your attacks, quickened by Zephyr, will ensure that you always have enough mana for emergency sniping and retreating with 90 Caliber Net.
If the enemy is armored (laning against Leona or having a tanky jungler, like Wukong), you may want to finish your Youmuu's first. Youmuu gives you some attack damage, some critical chance, and armor penetration. And guess what? The active has MORE movement speed!!!! With Youmuu, your dying days are over. You will be able to move around and snipe kills very easily.

Whatever you get next is up to you.

Why so much health in runes and masteries? This build has 0 - ZERO! - BAGEL! - defensive gear. None of the items carry armor or health. Why? A sniper is better off having more damage than armor. Your staple is not getting hit.
So why health? Easy answer. Before level 6, you don't have damage or speed. You are a sitting duck and you need to get kills without being killed. The massive amount of health in beginning ensure that you will not die even if you do happen to get ganked or something else happens - like when your friend, Lucian, brings some KFC and you happen to be attacked while eating that delicious chicken. MMM chicken. nom nom nom

Some people prefer guardian angel, phantom dancer, and runnan's hurricane. Phantom Dancer is a good alternative to Zephyr.

PD
Pros: High Critical chance, Can move through units, Attacks Crazy Fast
Cons: No attack damage

Zeph
Pros: Cooldown Reduction, Tenacity, Crazy Speed, Attack Damage with Attack Speed
Cons: No critical chance

For a sniper, attack damage is more important because skills do not crit (correct me if I am wrong).

As for guardian angel over youmuu or essence reaver, it is a matter of choice. If you are skilled, ward well, and can use youmuu well to evade tough situations, you will not die as often. Also, those who choose phantom dancer probably do so because they want to get in close and brawl - thus the need for guardian angel. For a sniper who does not get close to dangerous situations, but snipes from the outside (which is what a normal ADC, with the exception of maybe Graves and Vayne, is supposed to do anyway), you probably want the bonus damage and cooldown reduction from essence reaver.


Runaan's Hurricane is also a brawling item. It has nothing useful for a sniper. Attack speed and triple shot - 0 damage, 0 speed, 0 defense, 0 crit, 0 armor pen... if triple shot applied to Piltover Peacemaker and Ace-In-The-Hole, I would probably rush it, but unfortunately, League did not do it that way, so I do not recommend it. Now, in Hellgate: London, multishot applies to sniper rifles... but that is another story best left out of this discussion.

At the end of the day, how you decide to build is your choice. This is a guide on how to play the evasive, burst, sniper Caitlyn. Thank you for reading this far and enjoy!