Hi, I've been playing Kassadin for a long time - since level 18 and I am 30 now - so i would like to share the way i play him and give you some ideas and help you play him better. Since this is my first build please let me know the mistakes i have done so that i can correct them... Btw i may do some grammar mistakes because this is not my native language...
What I want you to know about Kassadin, who everybody started calling overpowered after SK Ocelote owned as him at the IEM New York tournament, is that he can be OP, but only if you master him. Everybody, even an unskilled player, can have a good score like 7/3 or 10/3 as Kassadin after he plays a couple of games with him. But, to be able to OWN like hell, take the game all by yourself and make your enemies keep saying "Kassa op, kassa op", you have to do some good practise. Kassadin is a difficult champion to play.

: I believe flat ap quins are the best choice for kassadin. early game, where you are quite weak, the extra ability power will give you an advantage. I have seen people that prefers flat health quintessences - i disagree, but this is also an options for the ones that would prefer 78 more hp. There is a third option: Greater Quintessence of Scaling Ability Power(as u will see i will put the ap per lvl option for every rune category - i will explain why at the end).


: The magic penetration marks are good for every mage and champion that deals magic damage. They give you an additional damage - also good for early game. You can also put Greater Mark of Scaling Ability Power for late game.


greater seal of vitality: For seals i choose hp per lvl cause kassadin' s base health is really low and 175 life more at level 18 is not bad at all. Just like every time, i give you the option to choose between this and Greater Seal of Scaling Ability Power. Greater Seal of Scaling Mana Regeneration or greater seal of replenishment are also good choices.


For glyphs i used to prefer Greater Glyph of Ability Power, but i finally realized that these ones give you 9 ap, and Greater Glyph of Scaling Ability Power give you 28 ap which gets about 32 with the Rabadons Deathcap



WHY I ALWAYS GIVE THE OPTION OF AP PER LEVEL RUNES:
I have count it, and if u have a hole rune page full with ap per level runes, u will have about 85 ability power at level 18(4 or 5 ability power per level). It' s as if u had one more needlessly large rod...

Now with the new mastery trees there are 2 options to play kassa: Utility or Offence. I choose the second option, offence, because i like to play kassadin agressivelly, i like to deal more damage and i need the cdr. So 21/0/9 is my suggestion.
If u decide to go with the utility(9/0/21), some of the points u should get are the movement speed, spell vamp, increase buff duration, cooldown reduction and increase experience.

THE FIRST ITEMS OPTION I GIVE YOU IS MOSTLY FOR NORMAL GAMES, OR, GENERALLY, NOT IMPORTANT-SERIOUS GAMES. SO...

1) I start with the Sapphire Crystal and 2 Health Potions. This way i have enough mana to spam my abitilies even early game, and with the pots I can stay at lane longer, or even gank other lanes.

2) My second step is to upgrade my Sapphire Crystal into catalyst the protector and maybe grab 1 or 2 potions to continue the lane phase. If my early lane face has been good i may have the money to grab the Boots.

3) After catalyst I upgrade my boots of speed into Sorcerer's Shoes or into Mercury's Treads, depending on how the game goes for me. If possible, i also buy a Blasting Wand for some extra damage.

4) Several minuts later i turn that Blasting Wand into Rabadon's Deathcap. From the moment i have that amazing hat i have the ability to kill whenever i want.

5) Since I know that I have my rabadons at about 20 minutes of game, and big teamfights are about to happen soon, i go for Will of the Ancients so that I can stay longer thanks to the spell vamp and give ability power and spell vamp aura to my teammates.

6) My next item is the Banshee's Veil, made by the catalyst the protector I already have, cause i always need some survivability(even if i rock). Of course, the reason i choose Banshee's Veil is not just the magic resistance, but also its passive, which blocks one negative spell every 45 seconds.

7) So... enough with the survivability. Let's now build some real damage. Staritng with Archangel's Staff i will have about 120 more ability power and i bigger mana pool(==> the ability to stack many times my ulti without prob).

8) Finally I grab the Lich Bane mostly for its passive, but also for the 80 ability it gives me. Once fulled my build im quite unstoppable, almost unable to die and able to win that game all by myself.

COME TO MAMA!!

THE SECOND ITEM OPTION HAS BIG CHANGES AT EARLY GAME PURCHASES. I USE IT ONLY IF I PLAY RANKED OR SOME IMPORTANT GAME WITH MY TEAM WHICH I WANT TO WIN.

1) I start with Boots and 3 Health Potions. This way i can go closer and farm minions faster and can also counter spam at the same time without having HP problems.

2) Kassadin has good base damage with his abilities, so i build him some health before damage. For that reason i go for the catalyst the protector as soon as i can. The protector will also help me at laning phase and mid game thanks to his passive.

3) At about 16 minutes of game i have turned the catalyst the protector into Rod of Ages. It gives me good ability power for the moment and im not easy to kill.

4) My fourth step is upgrading the Boots into Sorcerer's Shoes. After that I start my Rabadon's Deathcap.

5) At this time the enemies have already built some magic resistance, so i concider void staff] as a "must" item for [[kassadin.

6) Lich Bane is usually my next choice and the reason is the same as in the first build.

7) Just like in the first build and for the same reason again i grab the Will of the Ancients. Of course, its not necessairy to take it last, you can go for it after Rabadon's Deathcap or Void Staff.

Everyone has his own style and likes different items, so i am going to give some optionals:


: I would suggest you to pick this item only if the enemy has a lot of magic damage cause otherwise there are better alternatives.

: I have never used that item on Kassadin, but if the enemy team has champions like Dr. Mundo, who has a lot of hp, Deathfire Grasp active may won the game for you!

Zhonya's Ourglass: Zhonya's Ourglass is a great item vs an enemy team with many ad carries, like Ashe, ad Ezreal etc, but it can also save you from Karthus ulti- Requiem. Of course the 100 ability power it gives you may be the reason to take it anyway.

: You should never pick this items if you have taken the Mercury's Treads. Both items give you tenacity, but the effect does not stack and Mercury's Treads give more of it.

: I dont think that Kassadin needs cdr, but its your own choice...

: If you have a problem dieing too much take that item. It gives you 500 hp and 80 ap. Its a very good choice.

Passive- : Thanks to your passive you take 10% reduced magic damage(that's why Kassadin is also known as an "antimage") and you transform this damage into bonus attack speed(kind of useless for an ap Kassadin...).

: You throw a ball that deals a big amount of damage and silences the enemy target for 2.6 seconds at 5th upgrade. It is a great ability. It can be used for farming (last hitting) and it is also Kassadin's main source of damage. The cooldown is not big and you can use it whenever you want.

: This ability passivelly makes your auto-attacks to restores mana and when activated your auto-attacks also deal bonus magic damage depending on your ability power. It can be used to have the Force Pulse(E) charged and it can also be good for destroying towers(pushing).

: This is another very good ability. It deals very good damage late game and it slows the enemies in a cone in front of you. The only problem is that to be able to cast it has to get charged, which means that it is castable only after 5 spells are done by you or near to you. Although, in my opinion, if it was just like the other spells Kassadin would be kind of op...

: Riftwalk is Kassadin's best ability. It is actually a Flash that you can use every 6/5/4 seconds and it deals area of effect(a.o.e.) damage. Every time you use it within 7 seconds it deals additional damage, but it also costs more mana. I use that spell 70% for the mobility and 30% for the damage(since at 3rd upgrade - lvl 16 - it only has 120 base damage).

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- Just like most of the champions in LoL, Kassadin has a spell combo: R/Q/E (or R/E/Q). This combo deals something about 1000 damage vs carry dps champs late game and is very useful in teamfights. When Forse Pulse(E) is not yet charged and ready to do it, you can farm or harass with Null Sphere(Q)(without Riftwalking; dont waste your mana) until it gets charged up.
- Remember: Riftwalk is your best ability. It can be used to escape, chase and deal damage, but it will take you a while to learn how to use it the right way and not waste it(and your mana).
- During early game use Forse Pulse(E) only if you know you will kill at least 3 minions or if you have a guaranteed kill(or to save your *** with the slow of course).
- You are one of the few champions that have silence. Take the advantage and kick every mage's *** in the game. Don't let them get fed; make them feed you!!!

: I put Ignite cause i love the extra damage it gives. Early game i use it to finish low life enemies off and late game its useful vs Dr. Mundo, Swain and Fiddlesticks.

: I once had a game where the enemy team also had a Kassadin. When he and his team saw that i had Flash they all said i was a noob. When we both went at mid for a mirror fight, at the beggining, we kept harassing each other with Null Sphere. At level 6 i used Riftwalk to instantly go close to him, i did Null Sphere and then used Forse Pulse. The second he was no longer silenced he riftwalked away. Since he had low life and i had no mana to Riftwalk again, i used flash to get back close and finished him off with Ignite. After that he agreed that Flash is not bad for Kassa, but he said that its not useful during late game. However, i gotta totally disagree with him since the double blink( Riftwalk - Flash) makes you even more unpedictable and increases your escape-chase ability.

YOU CAN TAKE

: Its useless after you have taken the tear of the goddess.
: I used to use that instead of flash but then i realised that it cannot save me when i have 200hp and 3 enemies are chasing me. Plus it can replaced by Quicksilver Sash which additionally removes Ignite and Mordekaiser's Ulti- Children of the Grave.
: I would recommend that only if i play a ranked game and i know the enemy team has many ad champions.
: It can replace Flash or you can use it to combo these 2 spells to enhance your escape-chase ability.
: Take it if you are new with Kassadin and you are afraid of dieing too much.
: Teleport is good for every champion. Its useful for defending turrets and pushing lanes, but also for ganking. This last thing is what you should mostly do with Kassadin if you put Teleport on him: Especially if you are in an arranged team, you can tell your friends to put sight ward in bushes where you can Teleport and gank the enemies. This a great way to take easy kills.

YOU SHOULD NEVER TAKE

: Dont take CV. Let it for the supports.
: You are not a tank, so why would you take that???
: I do not want to talk about this one. I have only seen Rally once when i was less than level 10 on a Trynda who never used it...
: Too big cooldown, almost useless... NO!
: I know jungling Kassa may be fun, but i think its also impossible. Another spell you should never choose.

EARLY GAME(LVL 1-7)
I usually take the mid lane cause i can farm easily this way and i dont have to worry about the fact that my teammate may do something wrong and we will both die.
After a lot of games i realised that a good LeBlanc is maybe the only champion that can kill you easier than you can kill her. Of course you are both assassins with great damage, but she gets her blink earlier than you do, she can spam better and she also has a silence.
Anyway, the only thing you need to do early game is to LAST HIT. Its better having 0/1/0 score and 100 last hits, than having 3/0/0 score and 20 last hits. Just think that 12 CS will give you about 300G; just as if you have slained someone! However, if you know you can beat your lane opponent take the chance. Its some good extra gold that helps you get fed.

MID GAME(LVL 8-13)
Mid game is usually the time when both teams go in one lane and the first teamfights happen. The teamfights, if you have a good team, is a nice way to get fed up. What you have to do there is simple: After the tanks and the offtanks go in the fight, you Riftwalk in, Null Sphere and Force Pulse(focus the carries or the mages-NEVER a tank or offtank). If you see you are focused just use Flash to go out of there and, then, when your cooldowns are down again, do the exact same thing, which almost 100% of the times, if done right, finishes the enemies left and wins the teamfight for your team. At mid game you also deal more damage with forse pulse, which will help you at farming creep waves.

LATE GAME(LVL 14-18)
Late game will be a total party for you and your team if you have had a good early and mid game. Lost of kills and assists, lots of gold and many teamfights that you have to win by doing what you did mid game. In most of games you play, if you are a good Kassadin there is not gonna be late game. The enemy team will surrender early in the game...:(

CARE FOR: Enemies with magic resistance, especially Banshee's Veil, that blocks one negative spell every 45 minutes. When the enemies have more than 150 magic resistance and you have not Void Staff (yet) you are not capable to deal a lot of damage with your combo, and this is a big problem for you. So just dont focus them.

If you are not already a good farmer learn to be one. You may have had an awful score, but got fed cause of your many CS. Kassadin has good animation on his auto-attacks. Although he is not a good farmer at the beginning of the game. At early game wait for minions to go low life and then hit them to get the gold or kill them with Null Sphere or Forse Pulse). At mid and late game farming gets mush easier: You abilities deal more damage than before and if you are really fed you are able to kill about 15 minions just by using Forse Pulse once!

The way i play in a ranked game is totally different than the way i play in a normal game, because in normal i play for fun or to try a new champ and in ranked all i want is to win. So, what i suggest you to do in ranked games is not to care about the kills and focus on pushing, farming, and help your teammates. In almost all ranked games i play i go mid vs another mage(i always hope I will not have to face LeBlanc). This way i can farm alone, plus I am very good vs mages cause of my passive ability, so i usually own them.

So thats the end of my build. I hope you liked it and you found some interesting ideas in it.
In case you want to down vote it please tell me why before. I would like to know it and correct afterwords, or use your tips in another build i may create in the future.
THANKS!