Hello Summoners,
I present you my build of the new Jax.
I used this build a couple of times and it worked out pretty well so far.
(I'm sorry for my bad English, not my first language)

At first i want to talk about Summoner Spells.
I have chosen Exhaust and Flash.
Exhaust:
I take exhaust because of Jax his passive, his passive is that he increases his attack speed every basic attack stacking up to 6 times and it stays for an little while... if you use exhaust you keep attacking with basic attacks so you stack up more and more. If it's needed you can use Exhaust also for escape. You can Exhaust the most important champion and try to run and use Leap Strike to get away.


Flash:
As second Summoner Spell I take Flash, acctually I always use Flash with almost all of my champions. Flash is an good escaping tool and it's possible to catch up with your enemy's.

You can also use other sorts of Summoner Spells but i would recommend this two.
An other Summoner Spell that is optional is Ignite.

Ignite:
I use Ignite pure for finishing some kills of. You can also use Ignite at the beginning of an fight because it

For masteries I take 21/0/9 for some extra Critical Strike and Attack Speed etc. and for some increased Mana in the Utility tree.