Lux is the Counter to Zed/Fizz and the Assassin Funky Bunch
The strategy is basically to play like a complete pussy during laning and outscale him with a shitton of utility and aoe damage in team fights. Deny him kills in lane and roaming and Lux wins by default.
In the same way Lulu has strong waveclear and can deny kills with her shield and ult. Lux denies assassins with her shield, which incidentally has higher base and ap scaling than Lulu's shield alone. So level it second. She's also incredibly safe in lane.
The way you want to farm is like this. You'll want to do is throw an E out in a place where it'll hit all the minions. Stand in between the E and the enemy laner and auto the minions before the E goes off. You typically don't want to detonate the E before the full time because of the zoning potential. You typically don't want to try and auto the minions after your E goes off because it'll give the enemy opportunities to attack or harass. Rarely will you actually want to harass the enemy laning by popping the E on them if it's not advantageous to your csing. Another thing you can do, if you can't zone the enemy is to detonate your E as a minion is about to die. Then throw an E on top of it to entirely clear the wave. If you're forced to farm like this you'll be down in CS to the enemy laner, but you can be down 30 cs at 20 minutes. It's ok, you deal so much AOE and have so much utility it doesn't matter.
The goal of laning isn't to kick the enemy out of lane or get a kill, it's to deny the assassin kills and farm up equal to or almost equal to you. If Zed wants to he will outpush you. So it's important to have good wave control. Or even freeze your wave(pre level 6) in front of your tower. It's easy to freeze due to the Lux shield. The less risk you take the better. It's also incredibly important to let your side laners know when an assassin has left the lane. Spam the shit out of that ping. Also, always have a pink in the river or around flank spots. Even if you break even in lane and deny him kills on you, he still might get fed on side laners.
If you're vs an AP assassin, GREAT! Buy a chalice on your first back and you're gucci. If you're vs Zed or Talon, I've been building doran ring and clothe plus hp/mana pots on my first back and second back. You'll need that second doran ring for mana regen and crucially it'll give you extra HP if he wants to try to burst you down and the jungler tries to gank. Then you get your armguard into chalice.
Never upgrade the chalice. Sure CDR is great on Lux, you know what's even better? Damage. You won't need the cdr until you have respectable damage. Once you get a needlessly large rod you get both a huge shield and the damage you'll need to actually start poking people to the point they'll feel it. Until you get a deathcap or hourglass and voidstaff there's absolutely no need to upgrade your chalice. If you upgrade it early you'll be delaying your power spike and giving the assassin time to roam and get fed.
