Nocturne is a very strong jungler that shines from mid into late game.

Q: What Does Nocturne bring to the table other junglers don't?
A: Nocturne is a really helpful jungler with not only a speed boost for himself at level 1, but also with his Shroud Of Darkness (W) , He gets a good atk speed buff for the passive and a Spellshield which can absorb a spell. And not only does he have all of this at his disposal, but he also has a fear, which all around makes him a very strong jungler.


Q: Is Feral Flare a good purchase on Nocturne now?
A: You lost me at Feral Flare.... (yes, it's essential 'almost')

As Nocturne it is important to try to farm as well as you can. Especially once you are trying to get Feral Flare and after as well. With the new Feral Flare, it opens a lot of lee way with what you would rather do. Farm creeps for a while or gank nonstop. Either works.

As Nocturne if you decide to gank pre - 6, it is important to try to get your Q in a position where you can catch the opponent off guard or corner them. Then if they have some ability that can stun or knock back, etc, use your spell shield immediately. Then begin the fear.

It is very important that you rush Wriggle's Lantern as soon as possible and then boots of speed. Farm jungle until you get Feral Flare, and if you need to gank, feel free to.

Since most of what you will be doing now is farming in the jungle for a while, try to get Avarice Blade

With Avarice Blade, you are able to get a little bit more cash in your pocket per creep kill,
Once you can afford it, get Youmuu's Ghostblade. This item can not only help you gank lanes with the movement speed boost it applies, but also can help you kill enemies quicker with the Attack Speed boost as well.

After these items, you really want to bring the tankiness out in you.
Rushing Randuin's Omen, Frozen Lantern, and Spirit Visage are all very good items on Nocturne because Nocturne benefits from each one of the items substantially.


Additional Notes:

Blade of the Ruined King - A very good item on Nocturne because it grants lifesteal, attack speed, damage, and upon using the active, slows the enemy and gives you a movement speed boost as well.

With BotRK, I only get this item if my top lane/Support are tanky as well and I would be able to substitute some hp/resistances.

However I've been getting this item a lot recently seeing how it is a very good item on Nocturne and gives him a lot of kill potential.

It is highly suggested that with Nocturne, you go straight for the enemy marksman/APC.

What I usually do is start my spell shield and Paranoia right on top of the enemy ADC, then I will channel my Fear and activate BotRK just to assure they can't escape. (If they do, chase them down with DuskBringer).

Make sure you not only keep their damage dealers in the back and out of the fight, but make sure their tanks/initiators are not on top of your carries pummeling them, otherwise it will end in a very sloppy teamfight.

With the new jungle item Feral Flare, Nocturne is a really good jungler again, let's go over some pros and cons.

Pros:
Strong passive effects make jungling and sustain a lot easier. (Umbra Blades, Shroud of Darkness)
Very good gap closer (Easy to get to carries)
SpellShield
Fear, and movement speed boost
Bonus Attack speed from Shroud of darkness
Low Mana Usage on abilities
A Very Good Duelist in most situations


Cons:

A lot of damage comes from DuskBringer so if you miss it impacts dueling potential substantially.
The Fear tether isn't a huge range, making it somewhat easy for someone to get out of it, however with a 6 item Nocturne, it's almost impossible
Very long Cooldown on Paranoia