When i played Jax before his ultimate was up, and after the phantom dancers stopped giving dodge, he was pretty useless, you hadn't any Magic resist, and taking it would have ****** all your stuff (thing which has been set with the Hex Drinker now, a very useful item), all you really could do was take a maximum dodge and hope the ennemies were all damagers in auto-attack, but now that he has an active on his ultimate, things are a bit more easy for him.

Nonetheless, there's not a lot of builds taking his new ultimate in concern, or, from what I saw, they wasn't focused on attack speed, which is, I think, the best way to play Jax.

Oh, and by the way, English is not my native language, so, PM me if you find any mistake.

I've chosen some armor penetration dor the marks, it's always useful after all.

Then, the dodge seals. As you know, dodge is now counted for the magic resist your ultimate give you, and anyway, it's always good to have a lot of dodge with Jax for Counter Strike or just to show any Damage hero who's the Grandmaster At Arms.

And to have a little more attack speed i chose the glyphs, 5% at the beginning it's always useful.

Now the Quintessence: To have more life from the beginning is ALWAYS a good thing, specially with Jax, at the beginning you will harass and jump on your opponents, who usually won't like it and will hit you a bit.

Well, it's a classic mastery tree for Jax: a lot in offense to obtain the Havoc, then just what it takes to get some magic resist and a little more dodge in Defense, and, of course, the Nimbleness, which can be really useful, i can't list all the times it saved me or allowed me to make a kill.

Take at first your Jump, it's your escape skill, but you'll have to wait your Empower to make it an harass skill, as long as you don't have it you'll just waste mana without doing great damages.
So, next you take your Empower. Your objective is to upgrade it as fast as possible (without forgetting your ultimate, of course, upgrade it when you can).
For the Counter Strike, upgrade it when you can't upgrade empower. The only level which is REALLY necessary with this skill is the first. At his second level you should be at 25% with the Ninja Tabi.
No need to tell you about your Relentless Assault, upgrade it when you can.

This is a build i made fully based on Jax's ultimate.

First: the summoners spells. I think Exhaust is a good choice to prevent damages from skills and to not leave the opponent fleeing, or to flee, and Flash is a really great spell to escape from your opponents when you can't jump on anything.

I think the Doran is a very good way to begin, giving you more health and armor, which can help you surviving in early.

I don't think it's necessary to tell you why i choose the Tabi Ninja: Armor and Dodge.

Then begin to prepare your Gunblade by taking the Vampiric scepter, it will also give you some durability on your lane.

The Guinsoo is a classic too with Jax, upping your damages, your ability, and your attack speed, you will also win health due to Jax's passive.

Usually, if you're facing powerful casters, it's now you take the HexDrinker, then you'll go and kick some caster ***es!

If you're not facing casters, then take the Wit's end, you'll learn to love it: adding damages hit after hit, upping your Magic Resist, God, it's good to be a Jax with that weapon.

Then, you'll need some spell vamp, continue building your Gunblade by making the Hextech revolver. Spell vamp is very useful, you jump in melee then, with empower+leap strike, you regained half of your life back!

The gunblade is useful in the way your ultimate is counted as magic damages, so you'll regen your health very fast, also improving your damages, your ability, and winning a good itemskill to use to engage a fight just after your jump.

And the final: buy a BF Sword: you'll obtain more life with your passive and the BF Sword.
After that craft the BF Sword in a Blood drinker.

First a basic thing: Never go mid with Jax. He's not made for that.

In early game: Play very carefully, as long as you don't have your ultimate you can't engage fight, but you can still harass your opponents with Empowered + Jump, which do great damages.
Once you have Counter Strike use it to flee after an Empowered Jump, or to prevent the ennemy from fleeing if you can kill him.

In mid-game: Now that you have your ultimate you're really more dangerous. Do not forget to use it before engaging a Caster, coupled with your Empowered Jump and your Counter Strike you'll get kills easily. You're supposed to have your Guinsoo at level 8, and your Wit's end at 11, after these two you'll be becoming a nightmare. Do not hesitate to get the Lizard Buff, it can be very useful to you.

In late-game: Now you should be able to kill, kill, and kill again. And maybe Kill agin, i'm not sure about that last one...


That's all for it! I hope you'll enjoy, and give me your advices to improve that stuff, they're always welcome ;)