This is my first build so don't kill me D:
Well Kassadin is a totally awesome hero, he can slow, silence, flash and manasteal. But most people don't appreciate all his AP potential and use him as an ASPD hero which sucks because the only thing you would do is steal mana. YEAH DIS IS A AP KASS BUILD (purple flying things FTW)
1- Null Sphere: Kassadin fires an ethereal bolt of void energy, dealing damage and silencing the target for a duration.
This skill is awesome, big range, nice ap ratio and a silence. You can use this ability to harass, last hiting, silencing nunu, tryn and other heroes ulti...
2- Nether Blade: Kassadin's physical attacks steal a percent of his target's mana and he gains twice the mana drained from these attacks.
A good skill if you are like me and think Kassadin doesnt have a lot of mana, can be very anoying for mages to get silenced and then mana drained before they can use a spell
3- Force Pulse: Kassadin draws energy from spells cast in his vicinity. Upon charging up, Kassadin can use Force Pulse to damage and slow enemies in a cone in front of him.
This skill is absolutely AWESOME! It didn't get that nerfed in the last patch btw and belive me, having to charge this thing 6 times isn't hard, especially in team fights
4- Riftwalk: Kassadin teleports to a nearby location dealing damage to nearby enemy units. Additionally, multiple Riftwalks in a short period of time cause them to cost additional mana and deal additional damage.
Great skill when it comes to ganking and tower diving but dont abusse it, many people think you must stay in perma riftwalk but that's way hard after 6 or 7, use it to get in and out of battles wisely.
5- Weapon Mastery: Kassadin takes 15% reduced damage from abilities and transforms this damage into bonus attack speed.
Very useless in this build since we aren't getting lots of ASPD
The point on Nether Blade on early game is to steal mana from mage minions and sometimes from heroes.
1-Meki Pendant -> Philosopher's Stone: Good mana regen and some extra money. If you can get enough money you change it.
2-Sorcerer's Shoes: +20 Magic Pen, not bad.
3-Mejai's Soulstealer: KILL THEM ALL!!!!!! Really, you have to start killing a lot and get 20 stacks as soon as possible.
4- Void Staff or Abyssal Scepter: I prefer void for the 40% Magic Pen but i don't know...
5- Rylai's Scepter: Slowing flying balls are awesome and plus your RW they will have a hard time escaping.
6- Zhonya's Ring: Say hello to AP baby
Optional: Another Zhonya instead of philosopher's Stone if you have enough time and money
Banshee Veil for survivality
... i don't know
Masteries: well... i think something like 21/9/0 but i don't know...
Archmage's Savyy 3/3
Burning Embers 1/1
Archaic Knowledge 1/1
Brute Force 3/3
Cripple 1/1 (forgot it)
And maybe... Evasion 3/4?
I prefer Ignite and Exhaust or Teleport
Ignite: Awesome to get the guys that are way to fast for you and your mana and kill people when tower diving
Exhaust: Good versus people that get way too close like Warwick (use it when he ulti)
Teleport: Lane Control and you can try the RW supa damage tecnique but i don't recommend it
Early Game: Harash and charge your FP, when you need mana target mage minions so you can steal some mana (around 10 per hit). When you hit lvl 6, and i think round this level you get Mejai's, start killing but don't get greedy just because you got RW and you think you can escape, NO SIR! YOUR MANA SUCK! AND KASSADIN IS A FLAN! If you're gonna tower dive to kill someone do this: NS, RW, FP, hit, hit, ignite, RW out of tower range; make this when the enemy has half or lower HP.
Mid Game: Keep killing and getting AP, get golem sometimes and watch out for low hp heroes so you can finish them, bait in team fights and when you have low HP RW out of battle. If you're being chased RW through walls, some heroes can pass through walls with skills and flash but you're god doing that, they won't get you if you're fast thinker.
End Game: If you had a good early and mid game you will just blow them up with every spell, remember to hit a couple of times mages like Veigar during team fights to recover some mana and do pretty much the same you did in Mid Game.
Conclusions: Kassadin is one of the best killers in my opinion, he's hard to chace and kill and can deal a lot of damage with his spammable abilities.
BTW FLASH GOT NERFED: be happy that you (and Shaco) have your own flash ability and explode it that way.
I almost forget, RW "awesome" thingy: if you think you have enough time before your enemy get to your tower start spamming RW in your base (where you regen mana obviusly) and after 6 or 7 stacks teleport very fast to the tower and RW fastly on your enemy and blow him up. NOTE: ITS NOT AS GOOD AS IT SOUNDS BECAUSE AFTER 2 OR 3 RW YOU WILL BE NEEDING MANA
Hope you like this build
any suggestions are welcome