Nasus is one of the strongest champions in League of Legends due to how well he can farm with abilities like Siphoning Strike and Spirit Fire
How much damage he can take due to his ultimate and Passive ability that grants him passive lifesteal
Not to mention the stacking damage of Siphoning Strike and the great CC move wither
All in all Nasus is not a one trick pony like many champs are he is instead an underplayed somewhat undiscovered off tank beefy dps.

This build focuses on Nasus melee damage, mana conservation, and off tank / tanking abilities
If you are in need of a tank then use this nasus build for probably one of the best late game tanks that can still deal massive damage

Now that the formalities are out of the way one must understand why the items I picked and more importantly why no Sheen????

Let me stress this sheen is an amazing item for characters like nasus who need to pop an ability then strike with it in order to deal even more damage. But it is not used in this build because trinity force and lich bane just do not work as tank items. Trinity force would surely boost nasus damage, hp, ap, crit, movement speed, and attack speed slightly. However it offers No Armor No Magic Resist And Too Little HP for a tank item. Lich bane is straight up pointless because nasus doesnt get enough ap to use it nor does he eve need AP because spirit fire and his ult stack badly with it. Dont think im hating on sheen saying its bad for Nasus im just saying its not good enough and doesnt fit well enough for him to be the best tank he can be and Nasus is a damn good tank.

Now the question arises though why manamune of all damage items just replace mana mune with Trinity and then you get the great damage hp etc from it. Manamune gives Nasus the ability to have an almost unlimited amount of mana so he can spam his abilities. Many times I run into a Nasus who runs out of mana either laning or after a team fight and although sheen gives you a slight mana boost it doesnt add up to the 2k mana boost you get from Tear and Manamune. Manamunes damage is also quite helpful in getting you kills early game since siphoning strike will hopefully be farmed up as much as it should be.
The boots are completely situational you either want tenacity and magic resist for a cc heavy team or ninja tabi for the armor and dodge percentage its entirely choice driven.
Guardian Angel is a great item for any tank just due to the shear amount of defense it gives you, and he extra death will help you get away as well as initiate easier......
Warmogs is the item to get that will boost your health effeciently enough for the entire game. Its a great early defense for nuking and its hp carries on throughout the game pasively increasing as you last hit minions and or kill champions.

Sunfire Cape, Thornmail, and Banshees Veil are all situational and odds are you are going to take 2 out of the three presented items since they boost your HP and armor or Magic resist and hp and mana, or increase your damage output against a melee heavy team.
In all cases I like to take Sunfire Cape since it slightly boosts your dps as a tank and effectively stacks with Nasus' Ultimate just with less range than the ultimate itself. The armor and HP are both needed as a tank since many AP heroes can be countered by hp at the start and magic resist later on.
Force of Nature will be created after selling Dorans sheild for the hp regen and also for the final piece of Magic resist you will need especially at the end of the game since your MR over level runes will be finished. However Banshees offers the same MR so these two are also interchangeable ( regardless selling Dorans Sheild is a must to get 2 out of the 4 items )

With these items Nasus during his ultimate is nearly unkillable unless focused down by the entire team. His passive lifesteal and siphoning strike along with manamune give him the damage that can kill most ranged or ap squishies. While his ultimates lifesteal keeps him alive taking life from the entire enemy team and his armor and magic resist make him a formidable, damage causing off tank

The runes I use for Nasus are my typical melee carry/ off-tank runes since they focus on early game damage and late game survivability.

Since I dont typically go for Ninja tabi in sacrafice for more tencaity against all CC and the starting magic resist the dodge runes are a must because any well built enemy team SHOULD have melee heroes and a dodge is the best defense since a dodge means no damage at all.

Magic resist per level runes are also a must simply due to the fact that most champions do not have enough magic resist to survive a nuke from heroes like Ryze and Brand every little bit of Magic resistance helps

Damage and armor pen quints actually work pretty well for Nasus since he is in his most basic form a melee dps champion with off tank capabilities. The damage helps farm early game and also gives him more lifesteal and damage from SS. Armor pen gives you the ability to do damage to tanks stacking armor or deal even more damage to squishies.

Id like to get this off my chest now THIS BUILD REQUIRES SKILL IN LAST HITTING WITH SIPHONING STRIKE

Alright now thats done.....Nasus in his laning phase is great at lane control.
As and off tank like Nasus you must control your lane in order to get into range to last hit minions with siphoning strike. A good laning partner is always great but this build also works extremely well when soloing.

Nasus' greatest lane controlling skill is Spirit Fire an AoE attack that lowers targts armor and magic resist while also dealing moderate damage over time. It has quite a large radius thus making it great for farming and keeping enemies off of your minion wave. Make Nasus a bully in lane constantly popping spirit fire so you can last hit every minion.
Do not worry about early game harass from ranged champs like Caitlyn because your lifeteal starting health regen and hp will all keep you alive and well while laning. But that doesnt mean you can charge in and take damage always be alert for a skill you can easily dodge and be wary of ganks.
Wither is Nasus' strongest tool while defending himself or attacking since it continuously slows and lowers the damage of an enemy. It costs a lot of mana so use it conservitively and make sure to use it supportively as well as aggresively. Nasus must be passive while laning only attacking when your partner is prepared to.
The way this build works makes Nasus a champ that doesnt do heavy early game damage like a Nasus build with sheen. In a lane fight the process must go as follows.
1) Pop wither on the enemy you want to kill
2) Begin to chase and read the enemies escape route
3) Pop spirit fire in a spot you know the enmy will pass over when you catch up to them
4) As your partner does damage or you yourself do damage constantly be wary of SS cooldowns
5) The enemy should be dead and tower diving is never necessary and only a desperate option
6) If ganked during the asault or after Wither should be off CD so use it accordingly

One thing that is greatly noticeable in this build is that I primarily focus on leveling wither and Spirit Fire over the dps move siphoning strike....
the reason is why I stated you mus be good at last hitting. You should (if you are good enough) get enough farm from siphoning strike to keep its damage strong enough so it doesnt need levels. Instead buff your spirit fire since AP is never used on Nasus thus spirit fire gets no boosts other than its levels. Withers slow and attack reduction are all useful in early game team fights as well as spirit fires large reduction in enemy magic resist and armor.
DO NOT BACK UNTIL YOU CAN GET TEAR OF THE GODDESS OR MANAMUNE Tear and manamune are essential to this build succeeding and odds are your last hitting skill will grant you enough gold to at least get a tear by level 6. The mana is like explained above pertinant to Nasus and spamming SS will give you all the mana you need.

Nasus ultimate is probably one of the strongest in league of legends
Its utility is entirely based on how and when you use it. Here are just some of its uses and times
1) When close to death popping your ultimate gives you hp and lifeteal as well as armor and MR to survive much longer and pick up an otherwise impossible kill
2) In the middle of a team fight when surrounded so you deal ridiculous damage and also get basically unlimited health back
3) after guardian angel goes off to surprise an enemy team and increase your tanking prowess
4) Pop to initiate and or scare away enemies since its CD is quite low and can be used often
5) To boost your damage in order to pick up a kill in an early game 1v1 situation

Just a quick note on why I choose heal as a summoner spell

Heal though a truly nooby summoner spell is so very very powerfull especially in the situation I am going to describe to you that happens quite often when I play Nasus

I was stuck in the enemy team jungle with 1/4 hp and 1/2 mana with no one around and 1 enemy chasing me since I had recenlty picked up a different kill without the use of my ultimate.

The enemy was faster than me but my ult was off CD and so was my heal and ignite so I ran into the nearest bush knowin they would see me enter it as they would unknowingly fall int my trap.

Once they enter I pop heal and my ult as well as popping ignite , wither and spirit fire on top of myself. I was at half health and my ult was tearing them apart they had no chance and heal as well as my ultimate gave me a trick up my sleeve as well as a great escape tool. Ignite did the starting damage I needed as well as overall weaken the enemy

Any contributions you guys can make of this build either working or failing is more than welcome
Yes I want failures because each player has a different playstyle and this build may not work just tell me how you played and I can either help or direct you to a better build

I have using Nasus since I was level 8 and have tried countless builds and my own build worked the best in almost all situations though I do choose sheen if I want more damage

I do accept any construcitve criticism on the build details itself and I will be updating it with scores I get to show you proof that his build is the best.