An example of a game:

Marks and quintessences is basic AP runes, the seals is chosen for the extra sustain due to not having any health items these runes make Kassadin have 2k hp at lvl 18. And together with Seraph's Embrace aproxiamtely 2650 hp, which is very decent for a AP caster.

Runes page:


The most important in the build is the Glyphs with CDR, which together with the 3 % CDR in offensive and 6 % in defensive (9 % CDR), is getting kassadin a total of 5,89+9+15 = 29,89 % CDR and since he almost always have either a blue buff or blue elixir, he'll be 39,89 % CDR (extremely close to cap). The more CDR, the more spells can be used and the more effective his silence, slow and even riftwalk is (making it all the way down to just 3 seconds).

At the start, the flask, fearie, health potions, biscuit and ward (should be using as lvl 1 to watch out the enemies movements) really helps him staying on lane for a very very long time, while almost spamming his Q on his opponent. On the 1st back a Tears of Godess + Amplifying tomb or Doran's blade, all according to how well you're doing.

Early game a you'll have roughly 165-187 AP when DeathFire Grasp is finnished, an extra burst and most importantly the 20 % extra damage to all your spells. Meaning you can take almost any champ down in a split second, or at least with 2 rotations.

Mid game you should upgrade to Archangel as soon as you reach or is close to the mana cap on Tears of Godess, meanwhile you can get Rabadon DeathCap (if you're farming well). Once at least DFG+Seraph is done, you'll need to get Void Staff + Sorceress treads, since the 8 % from mastery gives you a total of 43 % magic penetration, and 7,8+15 from boots, you'll be able to lower 135 magic resistance, to (135*0,57-15-7,8) just 54,15 MR. Or an AD carry with 85 MR to just 25,65 MR.

Late game, your biggest danger is the high damage from the ADC, which is why you should collect Zhonya's Hourglass, both for the armor and most importantly for the active. Which will almost be ready all the time due to the masteries and cooldown reduction. Thoose you have 3 click-ables that can be used very often.


I've tested almost every common build for Kassadin on (lol.asmr.robot.com), and none did outdps this build:

Skill selection is very common (R>Q>E>W), prioritizing Null Sphere due to it's extra silence time and being very effective on lane phase, secondly force pulse for the extra damage and slow. And most importantly Nether Blade (4 or 8) being picked up as soon as you get Tears of Godess, to max it out faster and an extra burst:
- Q E Q E/W Q R Q E/W Q E R E E W W R W W

Having your damage abilities maxed at lvl 13, which is when Kassadin is strongest (mid game) and have to roam support either top or bot lane which crazy burst damage. You should start roaming already around lvl 8 if you get the chance to do so.

Masteries should be 9/0/21, and look like:

Pros:
- Good mobility
- Huge bursts
- Long silence
- AOE silence
- AOE damage
- (Uncatchable)

Cons:
- Weak early game
- Riftwalk cooldown
- Requires a lot of mana
- Requires good position
- Item dependant
- Hard to farm with

The item build with 3 actives, masteries with maxed out cooldown reduction of summoner spells and activated items have a perfect SYNERGY and making Kassadin the ULTIMATE ASSASIN. He's reaching his max potential due to Deathfire Grasp's extra 20 % damage, mana shield and stasis activate for being in trouble, meaning you can get a safe double-riftwalk out of almost any situation. Or just use it to not take damage while waiting for cooldowns to refresh. The most important in the build, is the DFG, which should be used very often due to its low cooldown and extra burst (it has only ~42 seconds cooldown).