Hi, this guide will show u how to smack face with a stick as Jax.

!!! This guide is also short because I'm a noob with mobafire. I'm only showing this because the combination of Wriggle's + Wit's End is everything Jax needs atm. The items afterwards can be improvised. !!!

Mark of Destruction provides more ArP and MP than pure mixed ArP and MP runes. Jax needs both. Yellow and blue are tanky runes cuz u need that more than dmg with this build, and get MS quints so u can get Sheen before rushing Zeal on Jax for MS.

I find 14/16 giving everything I want. I want the % ArP and MP + tankyness (with sustain from HP-regen) and summoner talents for ghost and heal.

The best way to build Jax atm is to get dmg through damaging items providing tanky stats at the same time early-mid game. With ur ult u will have over 280 armor and mr late game, which is more than enough resists.
PS: Rylai's slow proc on the ult passive.

Early game: If you are against magic dmg (like Shen, Vlad, AS Teemo, etc...) get Wit's End after Vampyric Scepter before Wriggle's. Remember to buy pots and wards at every B.

About boots: Jax is weak vs CC. If their team has no CC, and smashing AD, go Tabi.

U have no AP early game and W scales with only AP, Q scales with AD and AP, and E scales with AD, but you E increases in mana cost after each time you lvl it, and doesn't provide much dmg, only a situational dogde and stun. Your leap strike reduces in CD, it's damage is increased, and it's mana cost doesn't increase.

Heal + Ghost has provided me the best results. Ghost is better than Flash for melee champions for chasing and escape power. Heal is for baiting and dueling. When I kill someone in lane as Jax I've noticed I often don't need ignite, becuase Jax can't chase THAT well, and if someone is ignited, they will run. Yes ignite can be used to finish off people, but I feel I can finish him off manually if they stay in lane anyways. Heal is so much better for teamfights and generally surviving. Ignite's damage is low compared to your damage, so staying on a target for a longer time is more important. (1 ulti proc mid-late game does the same damage as a ignite...so).

Save ur E in teamfights. Don't start casting ur E > Jump in > instantly stun. This will leave u with nothing afterwards, and has caused most of my deaths in teamfights, which I have learned from now. Rather, you should jump in > save ur E for when they are actually focusing you, or you are in a desperate need for a fast engage which WILL lead to a one sided AOE fest for you, only then.

Jax ***** on melee champions, with a few (experienced) exceptions, like Riven, and probably WW and Shen because of their sustain-harass (untill you get Vampyric Scepter).

Jax is also a awesome counter to Fiora, which was the reason I picked up Jax again when she was released. Jax is also strong against ALMOST all melee champions. It's all about punishing them really hard if they try to poke you. Especially if it's casters/ranged (like Teemo, I've crushed one).
How to harass: W > Leap Strike > E to neglect damage and lastly a stun to punish them even more.