At the time of making this guide, I was lvl 26.
This is my first guide, and it is gonna be on my favorite champion: Nasus, The Curator of the Sands. I loved Nasus since the moment i found out that his Q gains damage when you last hit with it. This actually learned me to last hit. I actually like to play him more AD with loads of life steal than a tank, because he is already quite tanky from himself and with your CDR your ult Fury of the Sands will be up every team fight

PROS

-Huge Damage while still quite tanky
-Built in life steal
-He can learn you to last hit
-Ult is GOD mode
-He's a dog
-He says woof

CONS

-Will be countered by ignite
-If you don't get farm, you will be worthless
-A lot squishier when ult is on CD

I think this speaks for itself, Armor pen. reds Greater mark of Desolation for champion that try to counter you.
Armor yellow Greater Seal of Armor to have some early survivability, and the same for magic resist blues Greater Glyph of Magic Resist.
I take CDR quints Greater Quintessence of Cooldown Reduction of to get off more Siphoning Strikes and Ults Fury of the Sands.

I go 23/6/1 for as much damage as possible and some CDR while still having survivability. I get Improved Recall to get back to lane faster, to farm my Siphoning Strike more.

I get Doran's Blade for some extra life steal, hp, and attack damage.
Mercury Treads mercury treads: You just want to run around freely as much as possible to hit things and the extra magic resist always helps.
Then I get Shurelya's Battlesong for the HP and CDR, and escaping ganks easier or starting
Trinity Force: IF YOU DONT GET THIS ITEM ON NASUS PLZ DELETE LOL! that's all.
Then the two big items of this guide: Bloodthirster and Spirit Visage. This will make you nearly impossible to kill because you will have so much boosted life steal that as long as you keep hitting things, you wont die if you have your ult.
As last just sell the Doran's Bladeand get yourself a Youmuu's Ghostbladefor more armor pen, CDR, Damage, and a little bit of crit.
NOTE: game will probably be over after you get your Trinity Force, but if your lucky, and you get a very long match, this built will almost secure a win.
NOTE 2: I don't get Frozen Mallet, just because you won't need it, because you will taking red a lot late game.

I take Siphoning Strike at lvl 1 and max it first for 1 reason: DAMAGE
I take Wither at lvl 2 and max it second, the slow is so strong at rank 4/5 nobody will escape you
I take Spirit Fire at lvl 4 and max it last, I find this ability quite useless, I only use it to harass people a bit at the tower and preventing them to recall.
And of course lvl your ult Fury of the Sands when possible.

1: Use your Shurelya's Battlesong
2: Wither your kill target
3: Pop your ult Fury of the Sands
4: SPAM THE **** OUT OF Q Siphoning Strike

I take Flash for, if I'm not fully build or I don't have my ult Fury of the Sands up, the whole enemy team is chasing me, I still can escape. I take Exhaust to shut down the enemy carry, and than rape it.
Teleport is also very good when you are solo top, but I just like to take Exhaust
I don't use Ghost Ghost cause i already have Shurelya's Battlesong and Youmuu's Ghostblade

Well, guys and girls, this was my guide on Nasus. I hope you all enjoyed it and will use it in your matches as Nasus. Plz remember this was my fist guide ever, so don't be to harsh on me. But I do accept constructive criticism so if you see any improvements, plz let me know in the comments. 1 more thing: If you get a double kill or more yell in all chat: 'TIS IS NASUS!'. It will increase your damage alot^^.