Welcome to my build for Nasus, the curator of the sands.
Nasus is one of my favorite champions due to the fact that I can deal INSANE amounts of damage, without getting more than a Trinity Force in the category 'Items that increase my damage output.'

My reason for writing this guide, is that everytime I play Nasus against another Nasus, or just against Nasus, I always find myself saying: 'Jeez, is it me, or is he not dealing any damage at all?'

The reason why I think Nasus is so ridiculously good, is his Q skill, Siphoning Strike (SS or Strike for short), which deals 3 additional damage everytime you kill something with it. yes, that's right, 3 damage everytime, and hell yeah it stacks. This means that if we were to lasthit ALOT, we would be able to deal ALOT of damage right? The answer is: Yes. Now there are a few problems. First, The cooldown on SS is about 4 seconds at max level, meaning we would have to wait 4 seconds to get a farm on SS. So what I did, I take Ionian Boots of Lucidity instead of, say, Berzerkers greaves. This lowers the cooldown immensely, and since I buy Randuin's Omen later in the game, I'm able to use SS around every 2 seconds. That's right, twice as much, which means twice as much lasthits, which means twice as much damage, which (might) mean(s) twice as much kills.

Now, for the people who have been paying attention, in my skilling order, I have been maxing Spirit Fire first. Why you ask? Well, for laning purposes. If you take 120 damage per second for a few seconds (76 + 20% of AP), you might want to try avoiding the Spirit Fire, which means you can farm longer, and also have a bit of ranged capabilities, making you a backup candidate for mid / top lane.

After Spirit Fire, I max SS immediately. Wither isn't good unless you really have trouble catching enemy champions, which you shouldn't. When I max SS, I aim to have atleast 100+ bonus damage on SS, because from that point on, you can spam SS like there's no tomorrow, and deal insane damage.

Another reason why I spam SS is because if I get lots of bonus damage on it, I don't need extra AD or AP. Which means I can go armor or magic resist or both. Personally, I have played 2 games of all my games with Nasus negatively, and I have just once finished my build. Usually, by the time I get the Guardian Angel, I'm either carrying, or we already lost the game.

Early Game
Try to not spam abilities. use SS whenever you can lasthit with it, and don't hesitate to recall if you are low on health. You have to survive no matter what. Survival means less gold for enemies, and less time spent inactive. When you have enough money to buy your sheen, go back, and the r*ping has begun.

Mid Game
Try to use those Strikes on enemy champs to not only harass, but maybe even kill. do not use your ultimate if you're not absolutely sure you will get the kill. (Note that if you use your ultimate, you regain health, making it a good means of survival.) By now you should have your TriForce and boots and be working towards Guardian Angel

Late Game
You should either be carrying or losing right now. seriously. There's no such thing as a subcategory. As soon as you get Randuin's Omen or Thornmail, which can be switched as you feel fit, you should be unstoppable. (Don't forget to combine Randuin's Omen's Active and Wither to almost stop enemy champions.

Summoner spells
I take Ghost for escapability and chasing possibilities.
Clarity I take because of mana problems from spamming skills in midgame, and being able to make the most out of my cooldown reduction.
Clarity can be switched to your liking, ghost however, I would not switch.

Please help me improve this guide by giving me some feedback!