This lore is out-dated and is no longer considered canon.
It is seldom the case where a champion is defined by his actions after joining the League of Legends rather than before. Such is the case with Jax, for whom the argument could be made that he is the most prolific tournament fighter currently at the Institute of War. Before joining the League, Jax was an unremarkable soldier-for-hire. For reasons known only to the former leader of the League, High Councilor Reginald Ashram, Jax was put on the top of the list of candidates to receive a League Judgment - the interview process that either accepts or rejects a prospective champion. His Judgment was the quickest in League history, where the Doors of Acceptance glowed and slowly swung open as soon as it began. Jax faced no recorded Observation or Reflection during his Judgment.
Jax proved himself to be an immediate terror in the Fields of Justice. The self-proclaimed Armsmaster of the League rattled off a streak of consecutive wins that to this day has not been matched. A number of summoners in the League grew concerned that the perceived objectivity of the League of Legends would be questioned by the presence of an unknown fighter who was unbeatable. For this reason, the new leader of the League (following Reginald Ashram's disappearance), High Councilor Heyward Relivash, created special restrictions for Jax to fight under. This was something the League had never done before, and something which has never been done since. The burly fighter responded by imposing his own special conditions; as a means of protest, he permitted himself to fight using only a brass lamppost. Neither the League's sanctions nor his own has affected his winning ways. The League has since rescinded its sanctions, but Jax has not; he fights and fights well with his trusty brass lamppost.
"Be advised - there has been an outbreak of lamppost-shaped bruises in the League of Legends."
The most prolific tournament fighter at the Institute of War, the self-proclaimed "Grandmaster at Arms" rattled off a streak of consecutive wins 152 long. No one had ever achieved even half of that number before, but what made it even more remarkable was that he did so while fighting only 152 matches. Concerned the peace accords that ended the Rune Wars would be threatened by a fighter who was unbeatable in the arena, the League hastily banned Jax from the arena all together. But in the spirit of the Institute, the League eventually relented, stating that a champion’s skill was no reason to remove a realm’s access to the governing powers of the tournaments. Jax was reinstated, but with one rule: He is only allowed to fight with weapons the League deems suitable. For now, that list includes a lamppost, a chicken’s foot, a spatula, and a fishing rod.
Weapon Mastery: (Innate): Increases damage that Jax gains from items by 15%. Equipment Mastery: (Innate): Jax gains 3 health per attack damage and 2 health per ability power received from items.
Counter Strike: Passive: Increases Jax's dodge chance by 10 / 12 / 14 / 16 / 18% Active: Jax stuns surrounding enemies for 1 second and deals 80 / 100 / 120 / 140 / 160 (+60% of ability power) magic damage to them. Usable only within 7 seconds of dodging an attack.
Relentless Assault: (Passive) Jax's basic attacks increase his attack speed by 6 / 10 / 14% for a short duration, and hitting the same unit 2 consecutive times enhances Jax's next attack for 140 / 170 / 210 (+70% of ability power) bonus magic damage. Attack speed stacks up to 10 times. (Active) Grants 20/35/50 + Jax's dodge percent in bonus magic resistance for a short time upon activation.
Jax dodges all incoming basic attacks for 1.5 seconds. At the end of the effect, Jax deals 40 / 70 / 100 / 130 / 160 (+80% bonus AD) physical damage and stuns nearby enemies for 1 second. This spell deals an additional 10 / 15 / 20 / 25 / 30 damage for each attack dodged.