Sniper - Allyourtowersarebelongtome

Items

Starting Out - Early Game:

Get 2 of each Sage's Mask and Robe of the Magi to deal with your mana problems early game to allow you to continuously spam Shrapnel. These will eventually turn into an Orchid Malevolence. Choice of boots at this point would be Power Treads for the aspd and stats manipulation.

Core Items:

Manta Style for more tower downing power and Mjollnir for faster creep clearing.

Luxury Items:

Boots of Travel for mobility around the map.
Monkey King Bar for avoiding those pesky "Miss" while being able to down tier 3 towers from a safe range.
Assault Cuirass for more tower downing power.

Skills

Shrapnel is maxed early to maximize it's damage potential before it becomes less effective than your normal attacks.

Take Aim is gotten in conjunction with Shrapnel to allow you to farm at a relatively safe distance.

Assassinate is gotten whenever possible. When used in conjunction with Orchid Malevolence, the damage is quite significant.

Headshot is a good skill with a minibash and damage bonus from the minibash, but for this build in particular, your main focus is on towers, so it's rather pointless to get it early.

Summary

The most common method of Sniper these days is the DPS Carry Sniper but I say why give up the damage potential of Shrapnel early game and gimp your early game potential for almost no advantage?