Jinx is considered more overpowered than most recently released champions, and I think so too.
First of all her passive Get Excited!. It gives incredible 175% movespeed for assists/kills/towers that decays, one of the main reasons why jinx is so strong and actually very mobile.
Her Q Switcheroo! is stronger than her W and E combined, you get either attack speed or range AND AoE damage. First of all her minigun: it creates up to 3 stacks when she attacks, when you max it you are totally independant from attack speed items because you will have 1.5 attack speed with 3 stacks, the stacks don't decay all at once but one after another. Her rocket launcher gives her up to 700 overall range when maxed (50 more than caitlyn) and AoE damage that procs lifesteal AND crits, pretty stupid somehow but let's see what's left.
Her W spell Zap! has high damage, high scaling (140%), a very high slow when maxed and very high range with low cooldown, the only thing it can't do is going through units. It will also grant vision over the hit enemy, even when he's stealthed.
Her E Flame Chompers! deals damage over time and can zone enemies by rooting them when they step on it.
Her ultimate with the creative name Super Mega Death Rocket! is pretty similar to Ashe's ult Enchanted Crystal Arrow except it doesn't stun but scale with AD and the enemy flat missing health, that means it also scales with their HP.

Itemization isn't easy on Jinx since many items offer much for her. I think this build is a little better than most builds and items synchronize with each other very well.


Generally good on Jinx, rather bad in the late game though since you get % attack speed, you would replace them with Mercury's Treads late.


Jinx scales heavily with AD, while she can also poke easily with her rocket launcher, flat AD is really good for trading and burst, you have attack speed anyway thanks to your minigun, Bloodthirster fits perfectly into the mid game where Jinx is stronger than most ADCs thanks to the huge attack speed bonus. Also the sustain with lifeteal is very good for laning. The reason why you build Bloodthirster instead of Infinity Edge is because it costs less while granting pretty much the same power.


Standard item for the mid game at the moment, especially on Jinx it's very good since she does not need attack speed items in mid game. The percentage armor penetration has pretty much the same effect like building a second bloodthirster (except for lifesteal) while it grants even more power in the late game.


Pretty big item on Jinx, building crit is really effective thanks to her rocket launcher AoE crit. It's cheaper than Phantom Dancer and almost as effective, since Jinx can build charges quick with her extra Q attack speed (130% maxed). You can also use your range to poke enemies with its passive.


Jinx is the only champion that I would consider building Runaan's is smart on. Here the long explanation why it's broken: 1. She builds 3 stacks on her minigun with 1 attack 2. Her rocket launcher does not only deal AoE damage, the Runaan's shots will also proc the AoE damage that also stacks so that you can deal incredible amounts of damage with 700 range. Each bolt will proc the AoE damage, stacking with the AoE damage of the other bolts, dealing a maximum amount of 330% AD to a single target while the main auto attack can also crit (inclusive its AoE damage). The Runaan's bolts proc lifesteal (not sure if the AoE of Runaan's bolts procs it too, that'd be stupid) while the AoE damage of the main auto attack also procs lifesteal and crit. Basically what you do in a teamfight is spamming the heck out of your enemies with immense range, that makes Jinx the best late game ADC in the game right now.


Good defensive item, there are other choices like Warmog's Armor or Banshee's Veil though, dependant from the situation, GA just works mostly.


When you completed your build you want to replace Statikk Shiv with this item. Your attack speed will be almost at 2.5 with 3 stacks, so Statikk would increase it over 2.5 which is not possible. Infity edge is very awesome, just super expensive, that's why it doesn't fit into the build earlier in the game.


Can be neccessary when you can not kill tanks, the only thing that makes it different from Last Whisper is that it's good even as a rush item.

Pros:
- Good in mid and late game
- Runaan's Hurricane makes her a complete monster
- 2 forms of CC
- Doesn't need an attack speed item until late game
- Big sustain once you get lifesteal
- Great waveclear, pushing ability
- Gets a kill and runs away when low
- Stronkkk at level 1

Cons:
- ADCs are squishy
- No gapcloser escape
- Very player skill dependant, needs not only practice but also mechanical skill, not a pubstomper
- Can lose early games

Runes:
Flat resistances because of the weak early game, flat AD because of the high AD scalings and for lasthitting.

Masteries:
Points in crit masteries because of a decent crit chance with Statikk, extra tower damage since she pushs towers incredibly fast, points in armor and health for early laning.