I always look on Nasus with respect and fear when I find it versus me.

His composition of spell/abilitys and stats are really well composed that I think he can manage, with more or less pushing, all the situations that he can find.

It have almost everything that game can give:

• He's tank with well innate Armor, Magic Resist and by Innate Ability Life Steal.
• Q stack on minions kill, keeping him more dangerous as long as he farm well.
• Can disturb enemy farming and actions by a ranged area-effect E, that also power friend attacks up
• Ulti make him both more stronger and area-damage giver, in addition it go very long on time before it expires
• Basic Attack Damage, at last level, deal around 100 without any items, not bad for a tank.
• He can be build for frontface almost any situation: Easy enemy->DMG Tank, Strong enemy-> Full Tank, and so go on

This guide wish to give a suggestion on How To Think Nasus, instead of How to Build it, the above build(s) is only some suggestion to try it Hybrid, use it at your risk and versus relatively easy enemy unless you learn how to manage it.

Nasus is also very psycological champion: the physical-dominant (30% more with Ulti), the slow and the E can easy make enemy go confusing, or even feared, making him lose farms/kills or wasting Summoner Ability such as flash for escape W+E+R.
Never think enemy is too much smart: pressure and fear make them do stupid things.
You, as tank, are less subject to that kind of problem until you play tank role.

Nasus perform at best when enemy are mainly melee and they dont have hight sustain.

The above status, if combined with Attack Damage enemy team, make Nasus a Party's God that on Late Game will do 5v1 under enemy turret without big problems.

If enemy can fly/jump away, or they have melee skills that allow them to do damage to Nasus without expose themself to Nasus damage, Nasus is a less valuable choise for game and it's better to take another champion if you dont wish to have an hard lane phase.

Farming with Nasus is extremely paintful on early Lane Phase since la****ting and Q cooldown make you go out easily.

Don't give up, this is probably the worst phase of the game for you: Mana is never enought, Life and Resistance is low (and, directly, the sustain), you are also low on movements.

The skills in this phase are mainly 2:

• Cooldown counting
• Lasthitting

In deph:
Cooldown counting is necessary since you need to stack your Q as much as possible for lategame, this is a thing that will never expire on other phases: stack Q as much as you can until it's safe to do that.
Lasthitting is needed for stack both Q, for get gold when Q is in cooldown and for don't loose Q occasions: if you autoattack minions, he will lose life and maybe you must kill them with basic attack (so no Q stack) or minions kill it while you're casting Q or, worst ever, another basic attack; if you hit too much early, minions will keep a little life so Q don't stack and you will probably lose it also if you try to use basic attack.
Another problem is that, since you've not enought sustain, push lane forward make you more easily harrassable/gankable/fightable, so maybe you can still lose Q stacks and maybe life too.

Is all here the farming, read it and master it for perform good with Nasus in almost any situatiuon.
You can carry the game, keep that in mind.

The skill sequence is, also, very situational.

The most important thing you must keep in your mind is that your Q should be stacked as much as possible.

I suggest you to upgrade Q as the first skill, and do that unless you can easily manage Q lasthitting.

But, I repeat again, if you're on dobule-top formation, also W or E skill can be choise for max team efficence and maybe let your buddy archive First Blood.

E is also a valuable choise if you wish to invade.

W is a valuable choise if an enemy try to counterjungle your jungle and your team to to hunt him down.

Your abilities are perfect for teamwork.

Since you're not an assassin, is really a good idea to teamfight enemy instead of 1v1's actions.

Your E is a valuable choise and your W is also good for keep enemy far to your ranged champions such as Teemo or Varus.

I suggest this use of abilities for teamfight 5v5:

Since you're the tank, you're usually the first of the formation and you must open the teamfight with engage.
However, for psycological reason, i suggest you to let enemy team open engage: this will make him going near you and you can manage them better.

When the enemy team is near to you, start spelling the E where ADC (or the most DPS enemy champion) are.
Your team must focus him and take it down.
If he try to go away, slow him with W and maybe hit him with Q.

Next, cast R and E/W another cham, tank him down and keep him as much away as possible to prevent damage to your team.
Your Q are effective and should be used as much as possible to do damage.
Don't worry if you kill enemy, you're probably more valuable than a feeded ADC and if you take some kills it's not a problem.

I suggest you to do freehit enemys as long as you can handle damage properly: if you're low of mana, or you're low on gold, heavy underlevel etc. avoid tank them: Nasus don't have a good half-status, or he's good or he's bad, "TRY-TO" actions is not in Nasus logic unless he's not properly builded and had a well farming.

If enemy is really strong, i suggest you to cast R as first spell when you open teamfight for have less damage.