PROS:
-Great chasing with Duskbringer
-Ulti is great for ganks and scaring people
-Passive lets you heal moderately early game
-Great damage output late game
-Can 3v1 solo easily if there are not many tanks
-Can take turrets down with a tank on your team very fast
-Has a helpfull fear for runners

CONS:
-Doesn't have much of a damage output until first BF sword
-Fear takes 2 seconds to get off
-Can't solo more than 2 tanks easily
-NOT an early game champ unless you get a kill or 2
-Easily killable if disabled for very long (CAREFULL AROUND DISABLES)

Exaust - Great lowers armor with mastery makes kills easier
Ignite - That last tick of damage just to get your items
Ghost - Chase faster than anyone else ... almost
Heal - Okay but i feel like it makes people to cocky and think they are gods
Clarity - Ummmm...it's alright but you have runes for that

Last shot minions, jungle, whatever basic stuff.

Important items all are good BUT black cleaver is good but you can replace if necessary with last whisper or another blood thirster

Help your team in ganks don't leave them to die they will thank you and help when they can. Remember you have a high dps and lifesteal etc......

Early - Stay untill you can go back to get your attack speed boots and possibly Vamperic Scepter RUSH your BF Sword ASAP

Mid - After your bf sword lay on the pain ur ulti to gank people who think they can lane alone gank with friends for an easier kill/assist

Late - After the IE is done your passive can crit for alot in an AOE it hurts and dont forget to get a tank teammate for the turrets!<======= *hint* cant tank turrets for extended ammounts of time *end hint*

Usually when i fight other Nocturnes i find they go for the fear to lvl 5 first after duskbringer ... the fools never see you before they die.
Most importantly this is a 3 and 5s build you are a good asset to your team they need you and you need them never forget that.
You are NOT GOD YOU CAN'T 5v1 and win RARELY DOES THIS HAPPEN.