It was my First char that i played on this game and i loved him from the beginning i never failed him, i tried a lot of builds but this one works very gota till now.

Jax is very easy to play and Nice for First Bloods, in the beginning you do Leap Strike on them if they run away but don't do a Run by at the turret then you will surely Die.
Later you will use Empower first and 0.5sec later you do Leap Strike on them that will do a massive damage.

As for runes, you can either go with Ability Power marks, Magic Pen marks, Attack Speed marks, just based on personal preference. For Seals, Dodge synergizes really well with your Counter Strike, so those are a necessity. For glyphs I chose flat Ability Power, for an early game damage and health boost, the bonuses of which outweigh an extra 5.85% Cooldown Reducion. For quintessences I have recently begun using Dodge quints, which has been way better than flat health. I start the game with 12% Dodge just from runes and masteries, and by the end of the game you're up to roughly 40% Dodge, which is sweet.

Ninja Tabi
is the only recommend item you buy. It's just for the speed.
It has the normal movent speed 2, but it gives 25 Armor what is realy nice to have and it gives 12% Dodge whats very nice for Counter Strike.
Phantom Dancer
Is very nice because it has 15% Movement Speed, +55% Attack Speed, +30$ Critical Strike, The Critical Strike will be come more powerfull if you buy Infinity Edge.
Lich Bane
It is not so nessesary to buy this weapon because if you want to hit harder you can buy first The Bloodthirster. And later the Lich Bane but i recommend to buy Lich Bane First if you are a lot Low on Mana.
The Bloodthirster
The Bloodthirster is a very nice item for you dps, Because you hit so fast thanxs by Phantom Dancer so you will do great damage with it.
Never buy Infinity Edge earlyer then The Bloodthirster because you will need the Lifestealing.