Precision benefits Jax well, as it offers him the tools to deal with tanks and it's overall a nice set of runes.

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Lethal Tempo In combination with your passive and your R's passive, will enable you to do a devastating amount of damage to your enemies, giving you the ability to eliminate the enemy ADC faster than ever, letting you escape if needed and giving your team the boost they needed to join the fight. Vayne won't see it coming!

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Triumph is a good rune to have, since the whole build is aggressive, meaning you will do many kills and some more health after a kill will be useful both if you want to escape the fight or keep fighting.

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Legend: Alacrity This is obviously needed to Jax because will boost your attack speed more and more after every single kill you take, and combined with your passive and Guinsoo's Rageblade, you will soon be able to one-shot their annoying ADC that is focusing you from the very first team fight. Damn it, Caitlyn!

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Last Stand, since most of the times you have the ability to survive with pretty low health thanks to your E, this rune is ideal for you so you can take one down with you, or can help you escape in combination with Triumph if you manage to kill someone.

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Domination is a must-have rune set for an aggressive Jax like you, and I will explain to you why with details below.

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Sudden Impact is really beneficial for Jax, since it allows you to strike with great force, once you joined the battlefield with your Q. It can also be useful if you manage to surprise someone from inside the bushes. You can also combine it. What about striking them from inside the bushes with your Q? I'm afraid to ask.

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Ravenous Hunter This is one of the most important runes for Jax. Starting taking a very positive role in your game by the first minutes in the jungle, this rune will manage to give you a very good amount of heal every time you are doing damage with your W (that means every, more or less, 4 seconds) which is very handful, both in the early jungle and the late team fights. Combined with Guinsoo's Rageblade, it can serve you big amounts of health, making you almost invincible and fear to your enemies. Dangerous rune, handle it with care!

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10% Attack Speed is as much as it says. 10% Attack Speed, which is very good to have. The more attack speed, the better.

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9 Adaptive is a small yet useful boost, that will especially help you in the early jungle, for a really fast jungle clearance.

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6 Armor just like Adaptive Force, it's a small yet useful amount of Armor, giving you a small advantage in the early 1v1s in the jungle.