Kassadin is a great champion to play with. He can he used in various of different ways. In the following guide, I will be talking mainly about playing him as an aggressive ap hero.

Pros:

Free flash as his R
Good AOE damage E that slows
Silence from Q
Very good in team fights and ulti hits damage also while allowing escape.

Cons:

Q has a mana incremental count
Needs mana awareness and need team helping to get blue
Gets targeted quite often in team fights since you have OP silence

For the runes, I focused on mainly on three things.

Magic Penetration:

This really helps your game. In the beginning of games, high magic penetration really makes Kassadin's Q hit a lot of damage, WHILE SILENCES. Also since I am talking about AP build, obviously MP is awesome.

AP:

More damage the better?

Magic Regen:

Kassadin beginning game is very mana bounded. Unless team can help him get blue, he tends to need a bit of mana regen to give him the kick he needs to be able to use his Q and E combos along with ult to escape fights or engage.

I tend to start off with a Sapphire Crystal for the bonus mana and two Health Pots. Since the Sapphire Crystal builds into Catalyst, it's a good item to have.

Catalyst helps you have a strong beginning game with the bonus health and mana it offers. Carefully watch your exp bar. Just before you are going to level you can play a bit aggressively, maybe ult in, cast your E-Q Combo then hit him a few times. The level up should help you get your health and mana back.

Boots is totally up to you. Level 1 is definitely good, even if you have your ult. But some people don't like getting sorc boots first cause the speed is not needed, but the bonus magic pen really helps Kassadin lane strong.

The rest of the item ordering is totally up to you.

If the opposing team is a bit tanky and has a quite bit of damage, I would recommend going ROA first for the bonus health and mana. If they are easy opponents, obviously you can go Majis, or start building your Abadon's Cap for your insane bursts of damage.

Later on you can build toward Lich Bane, and usually, at least for me, the game ends somewhere after that, but if it drags on, you can maybe get Frozen Heart or Rylais for that extra boost.

Masteries are pretty self explanatory. Go for the regen and cooldowns. Along with cooldown for flash because it's such a good initiator for killing.

For offence that extra magic pen is really really really helpful in your beginning laning phase, and later on.

Depending on whether you are ganking lots, or are harrassing opponent laner, you can switch between your Q and E. I would not get W at all until the very end, even if it does help you recharge your E, it's a really useless spell in the beginning.

If you want to specifically harass opponent, then maxing out Q first is definitely good, even E is good for harassing, but it is AOE damage, so it will do damage to creeps too, hasting your pushing.

I love Kass just cause he is such a fun champion to play with and all his skills are so strong and has a silence and slow with a 5 second CD free FLASH!

Kassadin isn't the easiest to farm in lane, but he can get a lot of kills in team fights.

To farm kassadin, you really do want blue to be along your side. It really helps you spam your skills and get those gold that you need for your items.

If you do not have blue, don't fret. You might consider ulting into the minion wave, and caste E onto the back row creeps. That usually kills them, and if you have lots of items .. just casting your E will kill everything anyways.

In the beginning game, depending on who you are laning with, usually, Kassadin dominates all champs that lanes, but there are some that just keeps you back. If they are very aggressive, just be careful with your last kills, and if creeps are in the back, caste your Q to get that kill. When the time is right, flash up, use your R-Q-E Combo along with your ignite if needed to finish the enemy.

Overall, for me personally, I find Kassadin a really strong champion to play with. I have played with not a lot of variety of champions, but from the selection of AP heroes, Kassadin is one of the strongest, and a very powerful mid-laner.

I hope you guys like the guide, and as I play him more, I will probably up date it more often, and change around item builds, and add on efficient farming and ganking techniques.

Thanks for reading everyone!

Sincerely,
NinjaForm