Key:
Blue colored- titles
yellow colored- spells
red colored- items
green colored- summoner spells
purple colored- updates/ edits
ulti= ultimate or riftwalk
kass= kassadin
lvl= level
silence= nullsphere
'w' spell or armour pen spell= nether blade
slow spell= force pulse
ROA= rod of ages
cd reduction= cool down reduction
ap= ability power
ad= attack damage or 'dmg'
xp= expierence

Intro/play style:Here's a great Kass build I use all the time. You should try to pick up mid and farm creeps to lvl 6. You can also harass with your silence early aswell. Port back as soon as you get the gold and get your catalyst, It really helps you to stay in your lane and gives you much needed mana and maybe hp if your getting harassed to much. I can't stress enough that kass is much more superior late game and you shouldn't die more than onec in a solo lane. You can lane with a teammate but the same rules are pretty much applied. However, I strongly recommend that you try to pick up mid because kass needs the gold and he needs to lvl as fast as possible, to get his ultimate and his spells up, this is also why you get the catalyst and tear early, because you need to be in your lane, leveling as much as possible, not porting back to base every 3 minutes. The catalyst and tear, combined with teleport will keep you in your lane as much as possible. Fast leveling is also important because think about it, at lvl 5 your null sphere does about 300+ dmg and silences for 2.6 seconds!! This way you can make any enemy caster practically useless for 2.6 seconds and have more than enough time to drop them with your spell combo, your slows and ultimate can also help you catch up to anyone (except maybe master yi and his goddam ulti, that is, unless you can silence him first) and destroy them, I recommend staying away from mele dpsers, your somewhat tanky but your still a caster, dart in, spam spells and use your ulti to escape so you don't get dropped by people like tryam or yi. With kass's tankieness you can even turret dive, pick off a squishy who is turret whoring and escape with more than half health. THIS IS WHY THE BUILD IS CALLED NO ESCAPE!!! Anywhere from lvl 6 - 9 ( giggity ) is where you can start to get fancy with harassment and ganking. This is mainly due to ur ulti and there is a good move sequence that can pretty much kill and squishy champs with a successful gank. The sequence is as follows:

Spell Combo:riftwalk (to charge up for extra dmg) -> riftwalk in -> nullsphere -> slow spell -> armour pen spell (or 'w' spell) (kind of a throw away spell, but it can help because the passive will still remain activated) -> keep auto attacking and repeating spells till champ is dead.

About Kassadin and his spells:It's kind of interesting how kass works. He is a caster in this build, but his ' w ' spell and passive suggest a more physical dmg character. His slow can also help that. The point is, is that kassadin has a very high base ad, which is actually somewhat useful in farming creeps and even killing champs. I pick up kass's ' w ' spell at lvl 5 for it's passive, 4 mana per phyisical attack can give you more lane staying power and can really help you out. Also, kass is much more resiliant to other casters or people with stuns and silences. This is because kass's silence lasts 2.6 seconds at lvl 5 O M G! This allows you to silence the enemy caster, get in, do massive dmg and get out unharmed as stated earlier.

Items:Let's discuss items. I start with a sapphire crystal for the mana, again, for more lane staying power. This later builds into a catalyst for the same reason. Next, sorcerer's boots, obviously for the magic pen, which gets piled on with your runes, the speed from them is also a must (who doesn't have boots?). Tear of the goddess is for it's passive so you can get that going early, as well as the mana, it also builds into archangel's later. Mejai's is for the stacks and the massive ap it gives, if your not doing good you can skip it and get something else later. If you feel you need to be more beefy, you can get a banshee's vail in place of the Mejai's. Archangels is next, for the awesome mana it gives and its passive. ROA is to give you yet more mana, hp to give you more survivability, and ap. Zhonya's for the great ap, also, I always forget to use the active on the zhonya's, but it can greatly benefit you on any team fight or gank, therefore I would put it as your ' 1 ' key to make it easy to access. Finally, we have the rylai's crystal scepter. Now "why get this?" you say. This is because it makes you even more beefy, gives you a good amount of ap, and makes all you spells slow. Okay, I know that kass already has a slow spell, but the rylai's is worth it. You need to cast other spells before you can use your slow, so now you don't need to worry about spamming your riftwalk and 'w' when your in a chase or team fight because all you spells slow. Not to say that your slow spell isn't effective, it will still slow the enemy drastically and do massive dmg, so don't forget about it. (update) due to the new league patch zonyhas has been removed and 3 new items have been added. I now recommend getting a banksy's death cap. However, you can get the other new ap item too, if you feel you need to be more tanky. Also, the new boots complicate things a little. You could get the new cdr boots if you want. I would say that if they have more squishys and not a lot of tanks, you could get the cdr boots. If they have more tanky people I would just stick with the sorcerers boots. It's also preference, you can get either of the boots, they both work good for casters like kass.

Runes: O.K. now your runes. Magic pen because, well... they give you magic pen, what more is there to say, they help your spells. Health per level because it makes kass yet more beefier and gives him more survivability. Now ability per level because of the nice boost they give to your ap. Quints I have 1 ap per level and 2 cd reduction per level, self explanatory, they are good for casters like kass and the cd reduction helps kass use his ulti more to pick up kills and escape fights, they can save you, if you want you can swap the single ap quint for a third cdr quint if you want, it's more personal preference but make sure you get cdr per lvl. I prefer to get more per level runes because they are so much better. Most casters farm early anyway, and the per level runes already beat the base amount runes by lvl 6! Early game isn't that important, kass excelles at late game play, get per level runes!

Masteries:Masteries are self explanitory, standard caster masteries nothing to explain. Obviously, you should get extra experience gain for faster lvling.

Summoner spells:Summoner spells are teleport and cleanse, teleport helps you get around and not lose as much xp from porting back early on. Cleanse can save your life, kass's only escape is his ulti and if u don't have mana or there isn't enough time to get out and ur slowed, ur done! u can also decide to pick up ignite, heal, ghost or exhaust if ur not a fan of cleanse.(update) I now recommend using ignite instead of cleanse, after trying ignite in place of cleanse I see now that it is more worth it and more effective. You can still use cleanse or any other spells if you want, exhaust also looks a little better for kass after the new patch if you want to grab that instead.

Conclusion:That's about it, thanks for reading and using this build. Late game you should try not to die. Never initiate, leave that to your tanks. Kass is best when he darts in and out of battle with his ulti, spams his spells, and does massive dmg. Please don't thumb down without commenting. Hope you win!



THE POWER OF KASSADIN
http://img695.imageshack.us/i/leagueoflegendsepicmatc.jpg/]




*PROPS* >gotta respect killraven for the time he put into his build, I used to use his all the time and it's not bad, he infulenced me to make this build.
http://www.mobafire.com/league-of-legends/build/kassadin-badass-rift-ninja-11469

>also check out divineglimpse, he's a good friend of mine and I use a lot of his builds too. He also helped infulence me to create a build of my own.
http://www.mobafire.com/profile/divineglimpse-15244

>please check out my youtube channel here: http://www.youtube.com/professorownage1

EDITS: *1-4-11 new update removed zonhyas ring and added 2 alternatives. As a result I added a bansky's death cap in place of the zonhyas. I also have decided to add ignite instead of cleanse because you can use ur ulti to escape and if there are multiple enemies with slows/stuns on the enemy team is wont make a difference.