Karthus

Lux has a lot more range than karthus and can harrass him a lot while staying safe. Moreover, Karthus is very squishy and has no mobility. You can block most of his harrass with your W and 1 Q>E>R kill him

Ekko

Mostly easy lane for Lux. Your E has more range than his Q and if he uses his E on you, immediately use your shield and poke him. After 6 if you snare him he can't use his ult, making him vulnerable.

Katarina

Laning against an experienced Katarina won't be easy but you can win the lane. Harass her before 6 and avoid getting hit by her Q. Always be ready for her Q>E>W combo, so keep your W and Q. After 6 it gets harder to win as you need to be more carefull not to get low enough for her to use her full combo and in most cases she will go gank other lanes.

Fizz

Before 6 it's a pretty easy, harass with your E and never use your Q before he uses his Playful Trickster. Avoid long trades and use your W when he tries to engage. After 6 it's pretty one sided as he has way more burst than you and can easily kill you.

Yasuo

Yasuo can be a really strong counter. Either start with W or unlock it when you lvl up. Always stay way from your minions as he can E on you, never use your Q unless you are sure it will hit and if you see him come near you, use your shield. Try to break his shield with your basic and never go all in, unless he has wasted his shield

Zed

Harass him early on and never stay near his shadow. Use your shield when he comes near and wait for him to waste his shadow to Q him. If you see that he bursts you, go for zhonya first item and play safe.

Ahri

Annie

Akali

Gangplank

Annie

Blitzcrank

Nami

Morgana

Brand

Braum

Thresh