There are many ways to play Kassadin. I will be focusing on Pure Damage Ap for damage only. Kassadin can do a large amount of damage to the entire enemy team with his Force Pulse. He is also a great escaper using his ultimate, which has a VERY short cooldown and is able to go through walls. He's got a silence for other caster. So now that I've covered some of the things about him let's begin!

PROS
Great nuke
Great escape
Silence
Slow
A good amount of MP5 mid-late game
Passive is good with your Auto-Attacks


CONS
Mana hungry early game
Squishy
Being focused can be a threat

Kassadin takes 10% reduced magic damage and transforms this damage into bonus attack speed. This effect lasts up to 4 seconds.

Kassadin fires an ethereal bolt of void energy, dealing magic damage and silencing the target for a few seconds. Great against heavy casters that rely on abilities.

(Passive): Kassadin's melee attacks restore mana. This effect returns triple the mana against champions.
(Active): Kassadin's normal attacks deal bonus magic damage for 5 seconds. Great with Auto-Attacks.

Kassadin draws energy from spells cast in his vicinity, gaining a charge whenever a spell is cast near him, including his own spells. Upon reaching 6 charges, Kassadin can use Force Pulse to deal magic damage and slow enemies in a cone in front of him for 3 seconds. Great damage and slow but sometimes it takes a while to get stacks against a solo.

Kassadin teleports to a nearby location, dealing magic damage to surrounding enemy units. Each subsequent Riftwalk in the next 7 seconds costs 100 additional mana and deals additional damage. The cost and damage can stack up to 10 times. Amazing ultimate for a great escape and damage.

RECOMMENDED SPELLS

Great spell for FB and to finish off any enemy with that little bar of health that is just about to get away.

Another great spell to have. A double flash is very useful to get away or get in closer for a kill when the distance is just too long.

For times when your stunned, slowed or have any CC on you.

OK SPELLS

A good supporting spell that shows a place anywhere on the map and has a low cooldown.

If you like harassing a lot of just have mana issues then get Clarity. It should give you the mana you need to get through early game.

Gets you to where you need to go, but has a pretty lengthy cooldown.

Good for escaping when you are out of mana.

For the slow and if you have the mastery reduced armor and magic resist.

NOT RECOMMENDED

You wont need this spell. It just isn't worth choosing over the other spells up top.

Leave this spell out for a tank to take.

Another spell that you don't need. Of all the games I've played from level 1-30 I've only seen one person use this.

This spell has a 9 minute cooldown (I think that is I haven't used it in a while) so you won't be using it much within the game.

A great spell for junglers but not for Kassadin.

Damage Kassadin is a good nuker with high MP5 and mana. Also with a lot of AP for more burst damage. Your goal is to kill the carry or at least lower them down for your teammates.

EARLY GAME

Start off with and x2. I like to get Mid lane because you don't get focused down by 2 enemies and you get more EXP and can farm without anyone taking your last hit. I find that the first 2 levels are harder for me so I last hit my best until level 3. Then I get more into harassing with Null Sphere. I rarely harass with Force Pulse unless needed. If you run low just resume last hitting creeps and trying not to get hit by your enemy's spells. Gradually build your MP back up and then harass. Just repeat this until they seem low enough for you to take them. Then jump them with this combo:

Riftwalk>Null Sphere>Force Pulse>Auto Attack>Ignite.

If they made it through that don't worry, you can easily tower dive and kill them because chances are unless they have self heal, they will have very low health. Just Riftwalk in and Null Sphere then Force Pulse. They should be dead but if they aren't then they must be extremely lucky. Your next items should be Catalyst the Protector and . There are 2 options right now that are a good choice, gank top or bottom lane or just go back to mid and farm. Get .

MID GAME

Now you should have a decent amount of kills and be working on . Gank whenever you can while helping your teammates push lanes and guarding your own. Once you finish you should work on . The reason for this is so you get more mana for so you get more AP when you get . If teamfights start you should always be out of the initial damage. There is a certain point in teamfights when the most damage is dealt between both teams. You can tell this from all the abilities being spammed and cooldowns starting for the abilities. This is your time to strike. Target the biggest threat which is usually the carry while trying to get your Force Pulse around as much of the enemies as possible so the enemies are weaker for your team. Then just keep on killing and jumping out if you get into some danger.

LATE GAME

Now you should be building into whatever you think is appropriate with the two items slots left. I usually get one of these items . Is for the extra damage against enemies who have MR. For extra extreme damage and it adds more nuking ability. For the stasis when focused a lot.

So theres my Kassadin guide. He's absolutely disgusting when fed and done the build. It's not perfect and wont guarantee wins but I win a lot of games with this build. Any advice will be nice. I really hope I helped you and thank you for viewing my guide!