Early laning as kassadin is hard, especially against Ranged champions, so remember to just be patient.
If you do go in for a trade keep them short, since early on your abilities are quite weak.
Last hit with your Q from afar if your being pushed out of lane.
Wait for a gank or if you see an opportunity.
As Kassadin you snowball harder then a tire going down a mountain, so any kill or advantage you can get is a step closer to Control Alt Deleting the enemy team
With this build you will be especially weak early, but if you can survive to 6 that's when the real fun begins.

You started as Kassadin but now you are Kassassin.

Your W, Nether Blade restores 20% of your missing mana on a champion hit, it also resets your Auto Attack so in trades, Auto then W. W also increases your Attack Range

Your Q, Null Sphere suppresses for a split second, but that split second is just enough to interrupt a bunch of ults.[Katarina dashes to you and Rs, Press Q and she just ends up looking stupid.

Your E, Force Pulse is a blast towards the area in front of you and slows them to a crawl, But it requires 6 spells to be cast nearby that counts his own.

Use your R, Riftwalk to engage, Use it to Escape, Hell! Use it to Roam bot lane and suddenly appear on their ***.

The combo that works best is, R onto them, Q, Auto Attack, W Attack, E to slow, and R again or Q. This will delete champions and if things aren't going well you can R out.
Another Combo which takes advantage of the E more is, R onto them, E, Q, W, R, E. but it requires the enemy champ to use spells as well, which they most likely will.
Since W is a Auto Empowerment Ability it triggers the Lich Bane, and can do Ridiculous damage.

Around the 17 minute mark, depending on your kills and cs, you will be able to start clearing camps in mere seconds. I like to call this strategy "stealing from your jungler".

Depending on how your game has been going you will start to have a lot of fun. But don't have too much fun because you still are relatively squishy. Playing around teammates, Ambushing from behind, and stacking your R before you fight will ensure you get some nasty kills.

Play with your team and enjoy deleting squishes.

Muramana
This may seem an odd thing to build. Since Kassadin usually builds Seraph's Embrace, But the On hit Damage that is added by Muramana results in you out damaging Seraph's. Lich Bane also has higher AD Scaling so a greater synergy then just Seraph.

Frozen Heart
This Item will help you survive longer in teamfights while also debuffing the enemy team. the only tank item that increases max mana, which increases your AD bonus and your On hit damage from Muramana

Lich Bane
Great Item always build

Riftmaker
Provides OmniVamp, as well as increased damage if u can survive long enough

WIP