Hello everyone and thank you for taking the time to read my guide. I main Kassadin for at least 8 months. I've played numerous games to learn the new Kassadin so in this guide I'll tell you the build I found most successful and his new play style.

I'm just trying to quickly make a guide that will give the information, I will come back and update it visually later, most likely in the next patch that they make any changes to Kassadin.

Pros [*]Strong laning phase [*]High mobility [*]High burst potential [*]Easily Snowball

Cons [*]Bad positioning WILL make you useless in a team fight or get you killed [*]relies on team initiating then picking off squishies [*]Almost unplayable against AD mids

As mentioned before I'm keeping this short and simple so I can get this out ASAP but will come back to pretty it up later.

Core Build

Rod of ages is a MUST BUY now on Kassadin, it is the best item to get the mana you need, gives a good amount of AP at max stacks and the health is extremely important in keeping you alive in team fights.
Lich bane grants some mana but the more important part is the passive, even though nerfed it works perfectly with his new Nether Blade active.
It's Rabadon's, what else do I need to say.
The magic penetration is necessary in order to shred tanks and of course the AP
The active helps you lets you stay alive if you choose a bad time to jump in during a teamfight and continues to add onto your AP

Situational Items

Useful against heavy AP team comps
strong when there is a champion that is healing based on the enemy team, such as Fiddlesticks, Volibear, or Dr. Mundo
Useful when you just need that raw health to survive enemy team's burst

The new Null Sphere is still maxed first because the harass on it is still the most useful, but also the shield is the reason you are able to now trade and win lane.
Your key ability, it is a VERY important part to your burst, and also other than your shield the key damage ability when trading, and the main reason you are a complete lane bully now.
This is the same as before the rework, only a simple number nerf, it is useful for extra damage while trading, more importantly when trading it allows you to close in on a ranged target, also allowing for a good amount of burst.
Honestly, it's just a gap closer now, the fact that it scales with mana which severely reduces it's damage severely, on top of that the mana costs are now 75/150/300/600/1200 so you have to do 2-3 jumps then wait for stacks to reset.

It's so ugly it makes me want to cry, but please deal with it for now
This is the biggest change in Kassadin now in the past you would simply try to withstand the beating in laning phase until u hit level 6 then dominate your lane or roam. Now with his new Null Sphere and Nether Blade he can win trades easily and destroy the lane.

In general against all AP mid laners you want to actually save your Null Sphere until the opposing laner casts a spell against you, the magic shield activates immediately when you cast the spell, so if you have fast enough reflexes you can cast Null Sphere to block the damage then follow up with your Nether Blade and Force Pulse usually guaranteeing a successful trade.

The runes are for based on giving you maximum AP for late game damage, while having some extra sustain with the magic resist runes during laning phase.