This is a guide. It is not for and kind of play at all, it is just for fun. Yes there are tons of better guides, but this is more for humor than anything else. This is my first guide. Nasus is my favorite champion./color]

The enigmatic creature known as Nasus came to the League from a faraway world, and served as part of a vast and learned desert empire. There he was a respected and enlightened individual, having been made the Keeper of the Great Library. However, he was also part of a race of animalistic creatures that served as the rulers and protectors of the people. Unfortunately, there were others of his kind that believed they were more than protectors. They were under the egotistical delusion that they had ascended to become gods. War on Nasus's world was never more than a breath away, as these deluded others sought to enslave the people and establish a totalitarian sovereignty. In the midst of a heated battle, just as Nasus was about to slay his treacherous brother Renekton, he was pulled through the cosmos to a summoning circle in Runeterra.
At first angered that he had been taken just as he was about to cripple the enemies of his people, Nasus' advanced intellect won out when he heard the pleas for mercy from the summoners. He learned that Runeterra was also filled with its own brand of injustice. This danger was no less threatening than what he had fought against at home, and champions were needed to protect the people of this world. Heeding the call, Nasus chose to take his place in the League of Legends, knowing that his brothers and sisters would carry on the fight back home. These days, he is the Curator of the Sands, feeling most at home in the crumbling ruins of the Shurima Desert. However, recent disturbing news has reached the Keeper's ears - rumors that perhaps his brother had not in fact been left behind. If this were the case, the destruction of Renekton would quickly become Nasus' main priority, before this world too faces the threads of his brother's forked-tongue and endless ambition.

"The Curator of the Sands, though contemplative, is not to be trifled with."

Pros:

Does lots of magic damage

Lots of sustain

No more mana problems

Can do lots of attack damage

You cant run from him unless ur Kassadin

Awesome in team fights



Cons:

Not as tanky as he can/should be

Can be countered

Done for if focused immediately

Hard to build properly

Costs a lot

This is the most important part. You look for an explanation for this strange build. Well here it is.

Start: I suggest starting Doran's Shield for a melee attack damage enemy that probably won't harass you that much, like another Nasus or Irelia. Start Cloth Armor plus x5 pots for a melee enemy with a lot of harass like Gangplank or Yorick. Start Boots of Speedx3 Health Potion for a magic damage enemy. There are also some cool starts you can try if you follow a specific mastery page. Look at the mastery section for it.

Early Game: Go for full boots first, then Chalice of Harmony and Phage right after. Get Giant's Belt , and then Hextech Gunblade as your first full item.

Boots: You can any boots you want. Ninja Tabi for enemy focusing on attack damage, Mercury Treads with magic damage enemies, or annoying cc tanks. I suggest those.

Early Game: I suggest getting a [Heart of Gold] some time. Otherwise go for a early [Phage] and Chalice of Harmony. Then get Giant's Belt and get the Hextech Gunblade before either Frozen Mallet or Athene's Unholy Grail.

Now I will explain why to get any of the items.

Athene's Unholy Grail:
I shall start with this because this is probably what you are most confused about. It is also sthe most important item too, but only if you get all the other items in this build (except for Sunfire Aegis).

You will probably never run outta mana late game ever again, if you participate in teamfights. You will be less likely run outta mana early game because of Chalice of Harmony (this is also useful against an ap carry tops). This also has cooldown reduction. This CDR works really well with the CDR from Youmuu's Ghostblade. Nasus needs be able to spam his Q more, and not run outta mana when doing it after using his Ultimate and E, (which this item happens to increase the damage which both do), and his W constantly. Also there is magic resist which can never go wrong.

Hextech Gunblade: This offers both lifesteal and spell vamp, which helps his Q, and makes even his E sustain him in lane (because Athene's Unholy Grail offers ability power and CDR to do it of course). It gives more damage (needed) and ability power (needed in sync with Athene's Unholy Grail to make the spell vamp worth anything at all).

The slow is useful if your W is on cooldown (a shorter cooldown from Athene's Unholy Grail of course). Also I want you to see this. Your E does 622 damage total with 160 ability power(how much you have with Athene's and Hextech). Kassadin's Q only does the same if he has 500 ability power (8 more but so what). And Nasus's does aoe damage. So lets change to Zyra. Zyra needs 400 ability power for her ultimate to do the same amount of magic damage.

However, Nasus's does half initially and half over time, so health regen will make Nasus's do like 30 less damage (if the enemy is in it the whole time). If 2 of the enemies are in it the whole time it does 1244 damage and you are healed by 250 hp (not counting magic resist of course). Now for your ultimate. It does 75% of all nearby enemies health in damage to them, enhanced by ability power. It also heals you because of spell vamp. Also to note the more magic damage you do, the more attack damage you get and the more you heal from life steal(you know that Nasus gets 6% of all the damage done in attack damage temporarily).

Athene's Unholy Grail and Hextech Gunblade are the 2 most important items in this build.

Youmuu's Ghostblade: Damage of course, Nasus needs this damage because the rest of the build doesn't offer much damage. This armor penetration is a must have. Your Q needs armor penetration period. The cooldown redutcion stacks with Athene's CDR which is also incredibly useful for your Q (this item mainly superbuffs your Q). And there is the move speed and attack speed buff. This is useful for chasing people down (goes well with the ability from Hextech Gunblade). Also you can use it to beat the *** off an Ad Carry when he tries to fight you.

Frozen Mallet: Nasus needs health to be more durable. Nasus needs more damage. Nasus also needs the slow (which works well with Hextech Gunblade and Youmuu's Ghostblade, and his wither ability). Thats about it.

Frozen Heart: This item is awesome. Even more CDR, and a bunch of armor.

More Options Randuin's Omen, Thornmail, Guardian Angel, Warmog's Armor, or Sunfire Aegis.


Summary: Nasus is a tanky bruiser that does unexpectedly large amounts of magic damage and can do constant damage with his Q. If you try to 1v1 him, he will beat your *** off with his ult. He can deal damage to multiple people, and heal off it. He is still quite tanky.



READ THE LAST SECTION IT IS THE MOST IMPORTANT

Nasus needs it.

In defensive masteries, I immediately went for the 30 bonus health, which i suggest for Nasus

In utility masteries, I went for the move speed and gold per level. I would want gold per level for Nasus especially if you get heart of gold, especially because the items I recommend are quite expensive. I also hate a slow Nasus.

I have 2 other options here:

It is also important to note that some runes are "primary", while others are called "secondary" and provide lesser bonuses. Given a certain kind of rune, it will be primary in either marks, glyphs or seals, and secondary in the other two rune types. Marks specialize in offense, Seals in defense, and Glyphs in all magic runes, including magic resist.

Marks: If you farm your "Q" properly you are going to need some armor penetration, so Greater mark of Desolation.

Seals and Glyphs: Nasus is a tank and I like bigger numbers, so I got the Greater Seal of Defense and Greater Glyph of Scaling Magic Resist. You can get the regular ones if you want.

Quintessences: I thought a little more health, armor, and movement speed would work well. You can get whatever you want just be aware that Quintessence runes specialize in utility. So Greater Quintessence of Armor, Greater Quintessence of Health, and Greater Quintessence of Movement Speed

I focus on leveling my Q up as soon as possible after my ult. Next priority is W. It goes up to 97% attack speed and movement speed slow. This is the most op single target slow in the game. it will last longer than any other disable.

Teleport is amazing for [Nasus] period. Get to lane faster. Teleport gank bot lane if ur teammates put down wards.

Ghost: To chase down enemies obviously, or escape. It syncs great with all your slows, and your Youmuu's Ghostblade speed increase and Hextech Gunblade slow.

You can also get Flash, but I dont consider it as useful

You can get Exhaust, but that will only be useful early game. Your W slows more and can every 6 seconds.

This Nasus is awesome for team fights if played right. Follow him into battle. He does tons of aoe damage, and chases down people extremely well. He won't run outta mana in the middle of one. His ult is a killer. 5% of any enemies health around him every second and converts that into damage.

You have 35% lifesteal which is amazing and 20% spell vamp. Your Q heals off of both of them. Your E can do 600 damage to a single target, and your ult does 80% of a target's hp over time if they have 30 magic resist.

If you didn't notice already, YOU HAVE 50% COOLDOWN REDUCTION (actually 40% cuz thats the cap)
.You can use your Q every 2 seconds now. Your W every 5.5 seconds. Your E every 6 seconds. Your ultimate every minute

YOU ARE AN AD CARRY MURDERER.

Frozen Heart slows their attack speed by 20%. Your W slows their attack speed by up to 95%, and with 50% CDR, you can do that every 5.5 seconds. You can use your Q every 2 seconds, and your ult will do 80% of their hp (since they obviously aren't gonna build magic resist)

Lets talk about them running. You can slow them by up to 95% every 5.5 seconds (think about it, the slow itself lasts 5 seconds). You slow them by 40% every attack from Frozen Mallet. Hextech Gunblade slows them by 50% for 3 seconds. Your Yoummuu's Ghostblade increases your movement speed by 20% for 4 seconds, and you have 400 movement speed. Also you have ghost. Still think they can run?