This build is pretty particular, if you want to get the most out of it you'll want to follow the build guide to a tee, otherwise you may come out a little short when in the arena. So the build order will be laid out here for visual effect:
The Starter Items should be bought at the very beginning of the match before you leave the starting zone.
* Combat Boots - +10 Physical Power, +12% Movement Speed - Combat Boots should be your first purchase, this gives you some Physical Power, and Movement Speed while eventually upgrading into the Ninja Tabi early on.
Early Game - Ninja Tabi
* Ancient Blade - +10% Attack Speed - Ancient Blade should be the next buy on your starter list, it grants you attack speed while allowing you to prepare to upgrade into Winged Blade early on.
* Sprint - Gives you a way to retreat or help your allies retreat if you get into a situation you are dying in and backflip doesn't work as well as you want it to.
This is the first level 3 Upgrade that you get when you get the money to, you already have your Combat Boots that'll drop the price to 600 gold, which should be easy to get if you're actively participating in the arena match.
Early Game - Winged Blade
* Ninja Tabi - +20 Physical Power, +15% Attack Speed, +18% Movement Speed - The Ninja Tabi is an easy early game level 3 item that you can get that is -essential- to this build. Try to get it as soon as possible.
After you get the Ninja Tabi you should work towards getting the Winged Blade next, should you already have the Ancient Blade, so your winged blade should be able to be gotten at a cheaper price. If you are having difficulty staying in the fight and gaining the gold that is needed, you should go for the Adventurer's Blade.
Early Game - Wind Demon
* Adventurer's Blade - +10% Attack Speed, +7% Crowd Control Reduction, +7% Movement Speed, +150 Health - The Adventurer's Blade is the prerequisite to the Winged Blade, and can be gotten if you're having difficulty gathering the gold needed for you to get the Winged Blade.
* Winged Blade - +300 Health, +20% Crowd Control Reduction, +10% Attack Speed, +10% Movement Speed - Passive: When hit by a slow, you are immune to slows and your movement speed is increased by 20% for 4s. Only occurs once every 30 seconds. - The Winged Blade is the second level 3 weapon you should get for your arsenal allowing you to get increased health, attack speed, as well as movement speed.
Your last early game level 3 your should get will be the Wind Demon shuriken, this weapon is crucial to allowing you to let off your attacks quickly, while dealing your critical damage. Once you have this you'll have the means to be able to start attacking with a majority of your force.
Mid Game - Golden Bow
* Shuriken - +10 Physical Power, +10% Critical Strike Chance - Due to the price of the Wind Demon it is highly suggested that you buy up to it, starting with the Shuriken that allows you to deal physical damage and critical strike chances.
* 8-Pointed Shuriken - +15 Physical Power, +15% Critical Strike Chance - Much like the Shuriken this is a good build up to have to lower the Wind Demon's price even more, while keeping up with what you need to keep going.
* Wind Demon - +40 Physical Power, +20% Critical Strike Chance - Passive: Your crits now also reduce healing on targets by 40% for 3s. - This is the big mama of the Shurikens, you want this weapon not only for its Power and Critical increase, but also the passive it really screws over people who desire to heal your targets. Once you get this bad boy, you will begin the hard hitting that your build is meant for.
Now that you've entered mid game you should be able to get gold at a higher pace, so getting the golden bow should be no problem at all. That being said; like with the Wind Demon to not hinder your stats, you'll want to build up to it.
* Shuriken - +10 Physical Power, +10% Critical Strike Chance - Due to the price of the Golden Bow it is highly suggested that you buy up to it, starting with the Shuriken that allows you to deal physical damage and critical strike chances.
* Throwing Dagger - +22 Physical Power, +10% Critical Strike Chance - Passive: All basic attacks will also hit enemies within a 15 ft radius of the target for 25% of the damage. - the Throwing Dagger is a good weapon to have before getting the golden bow for the power and critical strike, as well as the passive.
* Golden Bow - +35 Physical Power, +10% Critical Strike Chance, +5% Movement Speed - Passive: All basic attacks will also hit enemies within a 15 ft radius of the target for 50% of the damage. (Note: Same targets can not be hit multiple times by a single proc of this item) - This is the first thing you should take with your mid game, it increases your critical to a point where almost every other hit will be a crit, as well as giving you the movement speed to run away and the power to deal damage.