Hello! I'm a Jax main on the NA server, and I figured that I would share the knowledge I've gained about this wonderful champion. This is the first guide I've made, so feel free to leave suggestions on how to improve it. With no further ado, let's get into the build!

Pros
+Strong duelist
+Great all-in past 6
+Gap-closer
+Stun
+Dominates autoattack-based
champions
+Decently tanky even when
building damage due to
ultimate

Cons
-Vulnerable pre-6
-Hurt badly by lane bullies
-Needs to have farm
-Limited CC and sticking power
-Not threatening when behind

Flash and Teleport are preferred. Flash allows for an instantaneous boost to chasing/escaping, and Teleport gives you extra pressure throughout the map as well as in your lane. This is especially helpful with the changes to Dragon rewards, where getting a lot of dragon kills snowballs the entire team at once. It's amazing to be able to help with objectives wherever you are on the map.

However, Ghost and Ignite are also viable to use. Ghost provides insane chasing power, while Ignite capitalizes on Jax's already strong all-in. These summoner spells bolster your offense, but at the expense of the high utility that Flash and Teleport give you.

The choice of items I've included in my build are based off of all my experience as a Jax main. Blade of the Ruined King and Trinity Force provide enough of a dps boost to let you dumpster anyone on the enemy team, even into late game. Thus, Jax can get away with grabbing 3 tank items after his core, making him an unkillable dps terror. When you build like this, it allows you to survive jumping into the enemy team during teamfights, and as they feebly attempt to focus you down the rest of your team will be free to wreak havoc upon them.

Now that that's out of the way, let's talk about the two cores, the difference of which being the choice of BotRK vs Hextech Gunblade. Now, it doesn't take long playing Jax to realize that the Blade of the Ruined King is just made for him. Attack speed, %health on-hit effect, and an active that heals you in the middle of a duel. Overall, it synergizes a lot better with Jax's kit than the Gunblade. However, the Gunblade does have one thing the BotRK just can't match: A 700 range, 3 second slow. This alone is why I would take the Gunblade over the BotRK, but there are specific situations where the extra range and duration are needed. Namely, it would be needed if there are high-priority targets on the enemy team who would otherwise be able to disengage from you easily when you jump on them (Champions like Fizz, Zed, Ezreal, etc). With the amazing active of the Gunblade, you can fire it at them from 700 range and simply walk towards them to close the gap. They will be forced to use their escape then, and only after that do you jump on them for the kill.

Overall, while the Gunblade can be amazingly useful in some situations, the BotRK is more suited to the way Jax plays.

For the most part, runes tend to be a matter of personal preference. The runes I take on Jax are balanced and useful in all games. However, it's perfectly acceptable to make substitutions based on your playstyle, like AD marks for easier CS'ing.

Same goes for masteries. The one's I've chosen are what I believe to synergize best with Jax, but you can change them up if you like to play him a little differently.

- Your W resets your autoattack. Always try to use it immediately following an autoattack to maximize damage output!

- You can also use this reset to finish off two low-health minions in quick succession.

- Your Q and E will drain your mana bar by a lot early on. Try to be conservative about using them in the first few levels of the game.

- Remember that you can re-activate your E for a quicker stun, or leave it on to absorb more damage.

- Once you hit 6, your power spikes significantly. You can afford to be more aggressive because of this.

- You can hit a minion twice, then jump to the enemy laner and hit them with a W-empowered third strike for a huge chunk of easy harass. You can use your E stun to disengage afterwards if they try to trade back.

- Your ultimate provides you with a lot of defense. Be sure to activate it when you're dueling.

Jax is a decent jungler, but his clears are a little on the slow side pre-6. Plus, he only has 1 stun for cc, so your ganks won't be anything extraordinary. So, with average clearing and average ganking, I don't really consider him as viable as other dedicated junglers. However, few can snowball as hard as a Jax can, and with red buff he'll give anyone nightmares. Overall, he's not the best jungler out there, but it can be fun to give him a go if you're tired of boring meta picks.