I'm not complaining but I just got back into playing Skyrim and have just finished the Thieves guild questline. I chose the Shadowcloak of Nocturnal and I'm not complaining but if I don't attack, or interact with an object while I'm standing up the cloak won't go away. It will go away if I do one of these if I'm invisible and crouching. The thing is if I keep this up even after the 120 seconds it will still be active. I have had the cloak on for up to 3 hours or more and it won't go away unless.

I mess up the rotation then I ended up finding the Ebony Mail which gives off a continous poison area of effect if an enemy is close by. It does 5 damage per second what I have found is I can literally stand next to an enemy or a group of enemies and while they are searching for me I can literally sit their with the Ebony Mail and the Shadowcloak of Nocturnal on they will slowly die and since it's an area of effect many enemies can all die slowly and at the same time. The other factor is that the poison effect does not count towards attacking an enemy while being invisible. I don't mind this but the fact that the Shadowcloak of Nocturnal can last me forever I believe it's to powerful I assume this is a bug.

Note enemies are still able to spot me and attack but that only happens ever so often. It's when theirs an enemy that uses magic or if it's an animal that I get attacked the most. Also even if your attacked and invisible usaully does not break effect unless hit excessively. Like I said I like being able to go invisible but the way it is now is to overpowered and I feel a bit bored with it. Theirs also the fact that is costs no magic to use.

I find that, if you're bored with it, it balances the power aspect by itself.

There is invisibility magic that lets you invisible, and basically magicka-cost version of that shadow cloak, and you can cast it over and over again and it gives the same result

I know their is but I don't have 75 illusion to use it, in fact I barely use magic unlike in Oblivion where I used nothing but magic. I have chosen to not use much magic in Skyrim however I figured that it says that it's spose to only last for 120 seconds and you can use only once a day. I would rather be able to have this effect then being able to use it forever being able to use it once a day will make it so that I will actually have to use it sparenly. I suppose I will just choose another power their's two others until this bug is fixed.

stop using the term overpowered, just stop. This is a singleplayer game...

Alright fine it makes things to easy

Select another Nocturnal power/equip another armor.

The term "overpowered" simply means "it is much more powerful than the average"
So yes, this bug combo is overpowered, and destruction is underpowered, but the latter is for another discussion

It has nothing to do whatsoever with the fact that this is a singleplayer game. A singleplayer game in which you can't be touched and enemies die merely because of your presence will NOT last although it's supposedly a "singpleplayer game"