Caitlyn is one of my favourite champion. I really like her 'cause of her range attack and 'cause of the really high damages in mid game.
This is my personal build of Caitlyn, I hope you like it.

p.s. Uh, I am a girl <3

With Caitlyn I use armor penetrations and mana regen runes.

Greater Mark of DesolationMark = armor penetration
Greater Quintessence of DesolationQuintessence = armor penetration
Glyph = mana regen per lvl
Seal = mana regen per lvl

You need mana regen if you want to use Piltover Peacemaker without losing too much mana.
With armor penetration you can do more damages in early game.

The summoner spells I use with her are Ghost and Ignite.
Ghost to run away after used 90 Caliber Net and Ignite if my ultimate is in cooldown (or if a player is really lucky).
You can use Flash instead of Ghost, Teleport or Exhaust instead of Ignite.

Piltover Peacemaker
Range: 1300
Cost: 50/60/70/80/90 mana
Cooldown: 10/9/8/7/6 seconds
Physical Damage: 20/65/110/155/200(+1.3 per attack damage)
Caitlyn revs up her rifle for 1 second to unleash a penetrating shot which deals physical damage to targets in a line, it deals 15% less damage to subsequent targets, down to a maximum of 60% damage decrease.

Yordle Snap Trap
Cost: 50 mana
Placement Range: 800
Activation Range: 150
Cooldown: 20/17/14/11/8 seconds.
Magical Damage: 80/130/180/230/280 (+0.6 per ability power).
Caitlyn sets up to three traps which trigger on champions. When sprung, the trap immobilizes the champion, deals magic damage over 1.5 seconds and reveals the target for 9 seconds. Traps last 4 minutes.

90 Caliber Net
Cost: 75 mana
Range: 800
Knockback Distance: 400
Cooldown: 18/16/14/12/10 seconds
Magical Damage: 80/130/180/230/280 (+0.8 per ability Power)
Duration: 1/1.25/1.5/1.75/2 seconds
Caitlyn fires a heavy net to slow down her target by 50% and deal magic damage. The recoil knocks Caitlyn back.

Ace in the Hole
Cost: 100 mana
Projectile Speed: 3200
Cooldown: 90/75/60 seconds
Physical Damage: 250/475/700 (+2.0 per bonus attack damage)
Range: 1900/2050/2200.
Caitlyn takes time to line up the perfect shot, dealing massive damage to a single target at a huge range. Enemy champions can intercept the bullet for their ally. It provides vision of the target for the duration.

I play Caitlyn with armor penetrations and critical items.
First i buy a Doran's Blade. Then I recall only to buy a B.F. Sword. You need to farm by last hitting minions. Don't push, Caitlyn is a good target in early game.
You just need to make money.
If you are mid, push minions and then go farm in your jungle killing Wolf or Ghosts, then go again in your lane waiting for the minions under your turret. By doing this you will be able to farm more then your enemies or your allies.
After buying a B.F. Sword you need Berserker's Greaves. Then buy Zeal and another B.F. Sword. You don't need Phantom Dancer for now, you need to have a high movement speed, a small chance to critical and more physical attack.
Buy a Black Cleaver then go for a Last Whisper. End the Phantom Dancer and finish your build with a Frozen Mallet.


When you play Caitlyn you don't need to be aggressive. Just follow your team and attack enemies from distance. When someone try to hit you, just use 90 Caliber Net, being sure that the net stops the enemy, to escape from him.
Use Yordle Snap Trap when someone try to run away from you by putting the trap in front of him (same use as the ultimate of kog'maw).
If you have a lot of mana regen, use always your first spell, Piltover Peacemaker to lower the opponent's health. Then hit him with your physical attack and if he runes away with low health, use your ultimate, Ace in the Hole.

Me (Ancetras in game).
Sorry for my bad english, I am italian.
I will update this build as soon as possbile with more informations!