Jax is a good off tank and dps.
A good jax is a jax hybrid.
This jax is a jax bag to hp.

Mark :
Hp for bag to hp

Steal :
Dodge for stun

Glyph :
HP for bag to hp

Quintessence :
Dodge for stun

8/22/0 :
Play jax with the masterie tank is good because Jax hurts automatically.
With a good resistance , you arrve to make the triplets , the quadruplets and pentakills.

Doran's shield :
For a good tank beginning game.

Ninja tabi :
For have a dodge for stun.

Frozen mallet :
For a input in hp , damage and decelaration.

Rylai's crystal scepter :
For a input in hp , ability power and decelaration.

Hextech gunblade :
This object is a object main for the hybrid champ.

Infinity edge :
This is object for the damage.

Rabadon's deathcap :
This is object for the ability power.

Exhaust :
This is the skill for all the melee.

Ignite :
It can often with Jax not to kill the champ with 25 hp because Jax is tthe melee.
So to avoid this , a small ignite and around is played.

Leap Strike :
This is a priority skill because for engagne in fight and to catch the enemy.

Empower :
This is a secondary skill because this is your skill for put slaps your enemy.

Counter Strike :
This is not worth to increase this skill because this skill used to stun.

Relentless Assault :
Ultiiiiiiii !!!!!
The ulti's Jax input a very good resistance magic and a increase dodge.

Pros :
-Carry
-Off tank
-Stun
-assassin

Cons :
I am looking for the default this is champ but I'm still looking.

This little guide how to play a Jax.
This guide is for those who love big slaps and bag to hp.
By the way, to make a pentakill with jax, you still have to have the reflexes :DDDDD