AHAHAHA dat pun made me laugh xD. Well justified thanks for clearing that up to dah viewers =)

The base MR of carries ranges around 30-40, even adding 50mr from banshee's veil giving them 70-80 max.
I doubt many carries will go beyond that in MR. In this range the benefits of void staff are null (sry, had to be done XD).
Even if reaching a range where void staff would actually benefit -you-, the MR it gives (combined with the passive), and the reduction -Aura- (meaning your whole team benefits, even AD characters considering many AD characters' abilities still count as spells), I do feel unless their team has an average of 100MR it is pointless to take void staff.
However I will add it to situational items as a special case scenario.

+1 forgot 2 mention.

Great changes although one thing. I am aware that you wont be focusing a tank. Many times AD carrys and AP carrys will buy mr to countrr you. Because of this you may be fighting a carry with 100 or more mr. Due to this you need voidstaff. Unless you always fight people who build glass cannon saying abysal is the only way is rather ill imformed.

Add item explanations, pretty well written guide.

@Agoney - I have throught about the difference between abyssal and void and also explained why I do still preffer the abyssal scepter.
As Kassadin I think you'd much rather focus on Carries rather than tanks, and carries almost always have very low resistance, meaning you'll see more results with abyssal. Also, If your team is built correctly you'll usually have another caster of any kind, making abyssal more useful as it reduces their MR for your teammates too.

As I stated about lich bane in the guide, It's actually not such a bad Item, and usually a really useful thing to get, the reason I usually avoid using it is because for the full effect I have to do some basic attacks in between and when combo-ing the hell out of someone (because a fed fiora for example can take me down really easy if I don't insta-kill her), the close combat against DPS carries (with life steal usually) is somewhat wasted on the survival Rylai's scepter offers.

I will add a situational Items section, because there are some really good picks. I just mainly made this guide to avoid the build on the top rated.

@LiLStormcloaK - Quite the contrary, if you build RoA you just benefit more from AA Staff. You get additional AP from the 3% mana, additional HP, and the additional mana pool (you get only regen and CDR from blue), making your Riftwalk more stackable, dealing more damage. Nonetheless blue buff is always a must and can save lives!

I think if u build RoA, theres no need for Tears/AStaff on Kassadin, blue buff will usually do the trick. Ur not someone like AP KOG or Karthus.

this is why kass is banned lol +1

Hey man, I really like what you have here. I am going to throw out a few sugestions though:

1- I would like to talk a little bit about your build. First off, please remove voidstaff from the do not get section. Grabing abysal when they have more than 130 MR pales in comparison to voidstaff. Here is the math.

130-(20+10)=100 MR

Void= 100-40% of 100= 60 MR

Abysal= 100-20= 80 MR.

As you can see it's drastically better to have void than abysal.

2- You need to offer alternate runes and mastries in your build. This is key to any good guide as some people may wish to take a diffrent path in this senario.

3- Consider lichbain to your core. This is up to debate, but the passive alon with your W is too stronk

4- Have some more situational items in your build, ergo warmogs, thronmail, ETC.

I would love to see you impliment these changes, PM if you decide to and i will +1 this guide.