Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Hey. I have been playing Caitlyn for a while now, and the most weak part of her is definitely her low survivability. Frustrated by getting targeted first in team battles and dying in a second, I decided to make her a tank while keeping her high dps intact. Surprisingly, this build is really good, and you should give this build a try before shunning it down. I hope you have as much success as I had with this build.
My last 3 games with Tank Caitlyn: Victory 3/0/12 Defeat 2/0/8 Victory 5/0/16
The reason for all critical runes is because you'll be relying on crit in early and mid games before you get Atma's Impaler. After you get the Impaler, your crit rate will go up to 40%. This might seem low, but you'll see many critical and it will have huge impact in late game.
Start with Doran's Blade and a health potion. You should preferably be soloing mid or top. When you make your first trip back to shop, you should have enough for both Berserker's Boots and Sword of the Occult. After getting those, your next priority is Warmog's Armor to gain much needed hp. Next is Atma's Imapler, followed by Wit's End. Wit's End provides the much needed AS with MR and additional damage. The last item depends on your preferences between Guardian Angel and Frozen Mallet.