Overview
Pocket is great at getting in and getting out while doing impressive burst damage. This build focuses on amplifying those traits by maxing Barrage (1) first.
This build was created by Vegas. To find it in game, search for "Mobalytics - Pocket by Vegas" (BuildID: 17361)
Early Game
Buy Headshot Booster and Close Quarters first in order to farm properly in lane. Pockets gun has a low base damage, so this will help you poke the enemy and farm efficiently.
Then buy Enduring Spirit if you need help surviving in lane. Otherwise buy Mystic Burst first for stronger poke and look to proc this on your cloak and satchel in lane when possible.
If possible save for Mystic Shot,which along with Headshot Booster gives you a lot of poke and kill potential. The damage these items do scale with your barrage's damage amp, so try and maintain as many stacks as possible in lane.If you are having trouble try buying Mystic Reach early to help out.
Once you are ready to roam buy Extra Stamina and Sprint Boots for better mobility.
Mid Game
Next you pick up Kinetic Dash and Cold Front. These two items give pocket a big power spike that should not be wasted, try and roam and look for ganks to snowball your lead.
If you are having trouble surviving buy Enchanters Barrier and Spirit Lifesteal.
This core of items should give us enough strength to save for our first 3k item which is Majestic Leap or Warp Stone.This is purely preference but I find Warpstone to be higher value, since both give mobility but Warpstone provides a bit more damage.
Late Game
We can look to upgrade to Improved Burst and Enduring Speed
Ethereal Shift is a great tool and should not be glanced over. This item gives pocket a way out after their initial burst and pairs very nicely with Warp Stone.
Divine Kevlar or Phantom Strike are your best luxury items, entirely preference and depending upon the enemy team's composition. If there are a lot of flying characters or weapon carries like Haze and Wraith, I recommend Phantom Strike over Divine Kevlar.
Situational Items
If the enemy team has a strong Yamato or Lash, I find purchasing Silence Glyph can help contain them while you finish your burst.
If the enemy team has high amounts of spirit armor, early Mystic Vulnerability is very helpful .