Not punished as hard.

When katarina is played mid, all of her all ins must be played perfectly other \wise the trade is lost. Top lane, everyone is melee and you do alot of damage, for a top laner

Less jungle pressure

Top is usually camped, or ignored. As katarina top, you are most likely going to be ignored. This allows you to go in more often and you are less susceptible to ganks.

Its a lot of fun!

A lot of top laners have never faced katarina, someone with reset-blinks and alot of damage. They are more prone to not return trades and you will be able to do whatever you want. + Phase rush is fun

More stuff:

You can bring TP for more map presence. You can pressure top really hard with your wave clear. You can escape all (or almost all) ganks with shunpo.

Tips and Tricks

Try to proc phase rush as much as possible

TP to other lanes with possible

Only ult when you are sure you can get the kill

Remember you can shunpo behind people, so you can dodge stuff like sion q

When going in, you lose long trades so go in then get out.

Useful combos are in this video: Katarina Combo Guide

Have fun!

Thanks for reading my guide!