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Nocturne is a great jungler. With his passive he can heal himself constantly on minion waves. His ult allows him to gank anyone he can see. this is my first guide btw, so please be nice.
Farm, farm and farm some more. Umbra blades can deal a lot of damage to a lot of minions, and it heals him, so he can farm even more. As a jungler, you want to get a lot of attack speed to triger his passive more often. Each minion wave has about 10-15 minions in it, meaning there is a lot of gold in one minion wave.
There are many viable options for a jungling nocturne, but the build i made is awesome. WIth wriggle lantern, you deal a lot of damage to the neutral monsters and with the additional life steal and Umbra blades, you'll heal yourself a lot. With the occasional critical strike, with umbra blades and wriggles on a minion, again you'll heal a lot and fast.
Attack speed and lifesteal are two things that are very important for nocturne. Both stack with his passive. The damage, attack speed, lifesteal, and armor pen from both the bloodthirster and the black cleaver should be enough to kill everyone and everything in the area. An extra bonus is that two out of three damage abilities stack with damage.
Once you get the bloodthirster the game is usually over. If its not, then depending on the enemy team i would get either an infinity edge or a frozen mallet. One is for making sure things die and the other is to make sure they dont get away while allowing you to take more abuse.
As a jungler, you want to be constantly aware of your team. Once your reach lvl 6, gank as much as possible. once you use your ult on someone always follow up with unspeakable horror, so the enemy champion cant run away. His ult cant reveal enemies, which is why he works really well with twisted fate. He reveals, while you and him kill something. He also works with shen as he can teleport to you when attacking someone alone.