Hello, this is my first build here and i hope it will help some of you.
In this topic you will see an off-tank Nasus made to have lots of survivability and pretty high damage . I strongly recoamend this build and champion as a Solo top option .

Note: I'm not one of the best players around i consider myself a medium player but i think this build is pretty solid for nasus so i thought to give it a try . I will update and add pictures as soon as i get free time , Thanks in advance and i hope it will be helpful :)

In this chapter i will talk about why , when and what is Nasus .

First of all , why ? Well , he can do incredible damage , great survivability and an annoying CC , especially for AD Carry's. He is one of my top 3 solo top options , a top where Jarvan IV , Irelia , Udyr , Shen , Akali and Kayle have place in it.

Second , when ? When you're team needs and Fighter that can keep the Top lane safe for a while, and do massive damage . I don't recommend you to have 2 fighter's , just in some cases when they do Jungle, then yes they are welcome :)

Third of all , what is Nasus? He is an Tank /Off-tank fighter, with a great ability to push and a self-sustained champion .

This Masteries Tree allows you have a extra boost on your damage output as well having some def boost. I know that 6 Armor/MR don't look to big but its for sure a good boost.

You can also have an Defense Masterie Tree , getting 0 . 21 . 9 with improved Dodge-> Nimbleness that would be grade against a team with 2 or more AD .

I strongly recommend not having an Utility Tree since, you don't really need it..

This set of Runes will allow you to be a good Off-Tank as well a Tank. I consider those rune set to be the standard Off-Tank set that can be used in jungle with a great result.

Marks : Armor Pen , i know this Champion dose not look as a champion that dose to much damage so that he can need this, but often you get tanky champions against you on top , so this would allow you to hurt them .

Seals : Armor . Its a must have on many champions especially Melee AD (Fighters) . I strongly recommend this runes and i think there is no good replacement for them as Seals

Glyph : Flat Magic Resist ,mostly same arguments as on Seal's but in this case its Magic Resist.

Quint's : Flat Health . Extra hp is always better, and on a tanky champions that suppose to have lots of Health is better:)

This is an harsh chapter, since there are lots of items that are needed in some situations .

Early game items :

The Pendant is a core item for the Philosopher Stone that you will need as soon as possible.
Boots : Mercury boots are very effective against hard CC and give a decent MR boost , but in some cases Ninja boots will do a great job too .
Heart of Gold : Decent amount of Health with GP10 passive.

I strongly Recommend GP10 item's. The gold that they give is very useful for you and theyr hp/regen helps too .

Mid Game:
Rushing to Sheen is not a must , you need to focus on Growing you damage on Q , But having it after the Early game items is very good.
Phage is like sheen an core element for Trinity Force that i recommend having before Zeal.
Trinity Force : You should be able to get it till min 25 without any kills and just the CS . Having this item will make your opponents think twice before engaging on you.
Chain Vest: The amount of armor it gives is strong, will make you very tough.
Negaton Cloak : You don't have too much MR without this so try get it ASAP .
Sunfire Cape : Great health , armor and a good passive.

Late Game :

Force of nature : One of the best solutions for MR , getting it will make Casters to think abit before wasting they'r mana on you..

Last Whisper : Damage and Armor pen , exactly what you need:)
Bloodthirster : Big amount of Damage and life steal that can grow alot,making it perfect to fit your passive skill

Flash is a must , since you don't really have a escape mechanism .

Teleport this can be swap with Exhaust , Ignite and in worst case Fortify but i don't recommend it.

Nasus has one of the best Q ingame . The skill allows you to farm very good and can stack up damage for each last hit you give (minion or champion) .
The W skill , is one of the best slows ingame , that give Movement speed and Atack Speed slow , that gets worst and worst by the time it applies .
The E skill : Is an AoE skill that gives poor to decent damage , that can be used to clear waves of creeps in mid game but that has an effect against opponents giving them reduce armor and magic resist while in the aoe range .
R skill . the ultimate. Nasus gets intro a rage form getting tones of damage near opponents , boosting his Health and giving procent based damage near him each second , for 15 seconds.

IMPORANT: Use the Q skill as much as possible , you need to stack it good to have a hurt people.

Don't start the fight unless you are strongly needed too . let the tank do that, eaven with off-tank items you don't need to be the one doing it!
The thing you need to do in a team fight is to slow the Carry , use the E skill to get as many people as you can activate R when you are near the fight(don't waste the time while its actived) and well target the Carry or what you consider is the best int that situation .

If you have a good tank , and you don't jump in , its hard to not be effective!

Get wards for you , you do not need to die in any case. Each time you go base get at least 1 ward , if the gold let's you get 2 , you can stay in lane alot , wards have limited useage ,
the more the better.

Don't forget you have a team , if you stay top all match and farm , its not necesarly a sucess for you or your team , try help when needed .

Tip : keep in mind Top tower is expendable but not over min 25 !!

Pros:

Strong
Tanky
Farmer
Insane Damage in mid-late
Very tough !!
Self sustained!

Cons:

Not the champion you would call early domination king .
Needs to farm his Q alot
Can die very fast till you get the early game items
Like most of the champions ... needs a brain to be played , and patience !

Thanks you for the support and that you read it!

I will add pictures . movie and all it needs for people to understand Nasus better.
Please vote and comment , i'm open to suggestions !

Thanks in advance ! Hope it helped!