Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
This is a guide on how to play mid lane champions , well, at least this is the way i play them. This is my 1st guide, so please accept the fact that i don't make good guides. So far I have only 4 champions in this guide, but i might be editing this guide and putting more champions in.
While laning as Katarina, you must your best to hit the enemy champ with your bouncing blades first and try to consume the mark with sinister steel, this was you can have the largest damage output from bouncing blades. When you hit level 3, you should do the bouncing blade - shunpo - sinister steel combo to poke the enemy. Don't be afraid to use your ult just to deal some damage, beause the cooldown is quite short, and you can use your other skills to kill enemies if your ult is on cooldown to reduce its cooldown by 15 seconds.
Malzahar is quite mana hungry, so watch your mana bar closely. Use your passive wisely, dont use it when you need to recall or roam around the map, because this way, the passive will be wasted and you would have to use another 4 spells to activate it again.
Like Malzahar, Lux is also quite mana hungry, especially Lucent Singularity, so watch you mana bar carefully. You can use Light Binding to snare enemies 1st before using your ult, that way you can have an almost 100% hit, unless your aiming is off. With enough cooldown reduction, you can also spam Lux's ult on minions...but that's more for trolling, unless you really have nothing better to do.
If you are against a champ who plays AP, or uses more of his/her skills than autoattacks, you should aim dark wind at him/her 1st, silencing him/her and not allowing him/her to use skills. Fiddlesticks also has quite little health, so when you drop low, you can just use drain. It is easier to land drain when you fear your enemies first. You can hide in brush or behind walls to channel your ult and then surprise your enemies with your ult - fear - drain combo.