This is my second serious guide. I decided to make yet another one, after my Seju's The Beauty on the Beast.
The reasons quite differ. I have not seen other nautilus guides and thus I don't know what's goin' on with them, they might be perfect. However, I love both champs and my conscience was burdened having made a guide only for one (yes, feel free to make fun of me, that's the reason :D ).
Story-time now. Once upon a time, there was an idiot (I don't remember details) that wanted to adress me in chat while I was playing Nautilus. In his confusion and rage he called me Nerulus. At first I found it very funny, so I started calling the champ like that. Now, after a year, I got so used to that name, that it is of my inconvenience to call him with his real one. So this will be how you'll see him in my guide.

(Here I'll say again what I use to say and I think it's very important)
This section can be a bit misleading, given that each player may evaluate a champion differently that others, and surely has a distinct playstyle, thing that affects evaluation over the champion. Anyway, since it's a build guide's trend, I'll also list some basic things.

Pros
dude, 1 stun, 1 aoe knockup, 1 drag (stun), 1 aoe slow (that's why Amumu cries)
health shield that scales with health
great tank throughout the game (is the definition of tank with his set of abilities)
awesome model and quotes (for me)
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cons
out of meta (very blue reliant, vulnerable to counter-jungling, mediocre farmer, early-gank-reliant etc)
weak 1vs1 duelist
supportive type of champion (gives chances to teammates to make plays. But you can't force them, can you? -**** bronze)

In my build I chose the Greater Quintessence of Percent Health because I love tankiness, but truth be said, in case of Nerulus, better ganks are pulled out with Greater Quintessence of Movement Speed.

The 6 points spent on utility are not negotiable. He really needs both movement and mana regen.
What you can change, is points on Sorcery for a bit more tankiness with Resistance .

Here I will list all the possible items for Nerulus and describe in which situation is each one made for. Before that though, a little bit of advice: If I recall right, he is recommended by Riot with Zephyr and Wit's End as agressive options. Every sane person would forget zephyr. But why not Wit's end?
Here's why: As you might have noticed, my build is "Tank Nautilus". And that thing gives no tanky stats, save for some magic resist, mainly built of autoattacks. You lose about 400 health that a defensive item offers. As far as attack speed is conserned, let's do a lil' maths: The bonus damage dealt with Titan's Wrath is actually a debuff lasting 2 seconds. Which in turn means you won't do more damage by increasing your attack speed, but with increasing your shield's strength (and thus duration before broken) with hp and for pure damage there's always ap.
Now about the list of items and notes:



An aggressive option, that offers a good amount of magic damage and magic resist. One would pick it when they have ap in their team apart from the player, to help deal more damage with the passive of the item. Remember never to buy it when another teammate has it, or is going to finish it, it's a lot of wasted money. Generally speaking I wouldn't advice buying it, since for tanks there is space for one damaging item option maximum, and that would probably be Liandry's Torment.


My favourite magic resist option, I highly recomend it. If you think you need some magic resist but don't want to spend a lot of money on it, buy it's first part ( Spectre's Cowl) and finish building it later. I believe it's more useful on nautilus than the familiar Spirit Visage because the passive of the latter goes in vain on Nerulus (he has no health regen lifesteal etc).


In my opinion, depends on the quints you use. If you have chosen Greater Quintessence of Percent Health buy the swiftness, else the mobs.


One of the most powerful tank items, offers an aura that can turn the battle. Nerulus though loves health, so I don't recommend it, but I still believe that if you have found an alternative build path or if you want to sell your jungle item at late game, it is a great choice.


While I was hovering over the lol item list, I saw frozen mallet and felt a shiver for some reason. Mmaybe my imagination, but I felt there might be idiots buying it. Just don't.


For most this explaination may be already known, but I'll say it for those who can't think of it. Guardian angel is, let's say a 'discouraging factor' for enemy champions when you tend to get focused. In case of tanks that's the desireable situation: to take the focus and the damage. So there is no reason discouraging them doing so.


Why on earth would someone buy it on Nerulus? His autoattacks do stun, and you wanna deal slow? Idiotic.. As for the armor, there are far better options (if you want a combination of amror and mana go for frozen heart with no second though)


I love this item. It goes like this: Want to deal some damage? Buy an early Haunting Guise and later upgrade it to Liandry's Torment.


What is Elise for champions is this item for items, I mean the changes and nerfs it has suffered are many. Yet viable under sir***stances (unlike -in my opinion- elise).
Buy it in two cases:
1. The enemies have a lot of magic damage dealers.
2. An enemy magic damage dealer is really ahead and your bronze teammates wont take any magic resist.
In the first case, buy it before banshee's veil. In the second case, and given that there is only that one enemy that deals magic damage, take it as your only magic resist option.


Cost-worthy, but it's not a final-build item, so you better focus on building something else. For example, if you want ap and hp go for the liandry's.


Not much really to say. A lot of health and armor, plus the cold steel passive.
Don't buy it only if the enemy has no auttoattack reliant champions other than the adc and the adc is noob.


Very good item. If you feel that you need armor, health and a lil' bit of damage, go for it. Remember though that in late game it's in most cases not enough and you will probably need randuin's.


If the thought of buying it even crossed your mind, uninstall lol. It alaready has too many of your kind for a game.


Your jungle item and the item you should max first (save for perhaps the boots?- that depends on your gameplay). You may want to sell it after you have done a full build for an item less oriented for jungle and more for teamfights and tankiness.


If the enemy is full of ad and you feel that your sunfire and randuins is not quite enough, go for this or the frozen heart. (enjoy ;))


Don't make it one of your priorities, but unless the enemy has %damage, buy it sometime. It provides a huge boost to your shield and general tankiness. Basically after this you will probably be the most tanky player in the game.

Nerulus's passive and by the way too op ( Braum cry you filthy *****). You can guess on your own how to use a stun.


Before you get accustomed to the exact range of this skill, I suggest you playing a few games with that thing on normal cast. And that because this skill is what defines most the value of a Nerulus player. A bad use will put you to a disadvantage, as it has a long cooldown. Here' re some tips 'bout it:
Using it to an enemy will drag both you and him in the between of your distance. That means that if he is on the edge of a turret range, you will drag him out of it.
If he is behind a minion, you may want to smite the minion and the use this spell. You may also flash over minions to cast it and catch the enemy by surprise. Do these only if you are sure of your skills though.
Casting it on terrain will drag you to it. This includes turrets, inhibs etc. Have in mind that even the **** (d-y-k-e*) between the river and the blue camp counts as terrain, don't think that you will grab a player behind it (it differs to Blitzcrank's rocket grab).
Don't use it to farm, asit has a long cooldown, it is an escape mechanics and deals very low damage (at first level 60) so an autoattack will probably be more damaging.


Very strong spell that offers too many things. Use it to avoid lethal damage or turret aggro. Also, when farming, activate it after the stun from your aa is cast on the strong monster to use the shield to its fullest. When enabled, don't autoattack the strong monster, but distribute a stun to each of the smaller monsters. The debuff will hit the large one as well, but you will stun/deal more damage to the others as well. These may sound like useless details, but remember that every second in lol counts.
Its other uses should be very obvious to you, and I don't think they are worth mentioning.


Be careful to cast it when the enemy is very close to you or is coming towards you, else you wont find target. For example, if you hunt down someone and he runs the same direction to you, only if he is stuck on you will he be hit by the spell, as the waves move a bit slowly outwards from Nerulus.
When farming, cast it and immediately walk a couple of steps away from monsters/ minions to hit them with all 3 waves.


Use it to initiate ganks (where the chances are above average of being succesful- its cooldown is very long), to hunt down fleeing enemies. In teamfights, initiate with thhis, aiming for the carries or for someone behind them (make sure you knockup the carries though) and then walk straight towards them. You should have reached them by the time the cc has ended, so then aa them for the stun. Keep on stuning key-opponets and remember to protect your team's carries. In most cases, a well played Nerulus is a won teamfight, and a well played Nerulus means well-landed cc. Keep those in mind.

*I'm not the best english user, but why on earth is this word banned? It seems it's a curse, though I've never heard of it. Sorry though, it's the only way I found expressing that place so the hardcore fans of proper language please forgive me.

I have both bad and good news for everyone new with Nerulus that reads my guide. The bad news are that he can't do sht without his teammates. As I said before, he is a supporting-type-of champion, at least played the way I propose.
In short, it means you should under no circumstances play him in Bronze or Silver Divisions soloQ. Excuse me, but I don't want to go into detail about that. Most of you will understand.

The good news are that he is one of the best junglers when the team co-ordinates well. And the better you do, the better he gets. There is no other jungler that can pull out tricks like Nerulus does (hello Lee Sin).In a sense, he is the excellent cc tank for ganks and teamfights (nope, it aint Amumu, amumu has no targeted hard cc, is less tanky and has only one and a half stuns, all his cc). Those of you who go on premade duo, you better install a skype, and you will reach a high elo with him.


If there is anything you want to ask, etc about Nerulus me or the guide, feel free to.
Also let me know of any add you want to the guide.