Super Power... With a Flaw

... But a strong smell of rotten eggs waft out from your nose 

I am invulnerable

To bricks thrown at precisely 200mph

I can turn into any character from any show, and can turn back at will, I gain all their powers and abilities

...But at the price of having their memories(not your own), therefore being unaware of this power, or your previous identity.

The ability to cast mage hand at will

however, the mage hand is permanently stuck doing the birdie.

I have an undisclosed power that you cannot determine or twist.

But you don't know what it is either, and you never will

I have the Lucky feat in real life 

Unfortunately, it doesn't recharge. Ever. All your good luck is gone once you use it.

I can shrink the line to any bathroom I choose.

But only bathrooms for the opposite gender of your own (If you are neither male nor female, your power does nothing)

I don't have Insomnia, and I don't have any Phobias, Allergies, or Intolerances

... Every even day. Every odd day, you have insomnia, every common phobia, every common allergy, and every common intolerances simultaneously. 

I can access any given tome at Will...

Sadly, because Will is a person and not a library, there are no tomes in him, so unless Will eats a book, your power is useless

I can swim at five times the average swimming speed of a human

... but only in tomato sauce

I have access to wild shape in real life, like I was a level 18 druid

... but can only turn into weak animals and can’t ever turn back. 

Anything you say is instantly translated to a language the listener(s) understand...

... but it always comes off sarcastically rude.

I have a non-sentient warhammer with similar capabilities to whelm.

... but it always spawns another copy of itself every minute, and those copies spawn copies, leaving you very overwhelmed. 

I have a version of the Eye and Hand of Vecna that is good-aligned...

But to put it on, you have to remove both eyes/hands, but you only replace one with the item.

I have the outstanding power to be able to speed up and slow down time at will, but anything I dictate right before I use the power can move normally despite the speed change

...but you don’t have anyone to *dictate* it to, meaning everything, including you, moves at that speed. 

I have the power to change into whatever form I want and can turn back whenever I want to. I can use this power as many times as I want to. 

(Dictate just means to say or read aloud)

But because you aren't technically you while in another form, you never technically want to turn back, so you can't.

I can instantly find the page I'm looking for in a book (Ex: If I want to find the page where it says the rules for falling, I immediately know where to part XGtE to find that page)

[Dictate: say or read aloud (words to be typed, written down, or recorded on tape). If you aren’t doing any of those things, it isn’t being dictated]

...but that page is always ripped out of the book you’re looking at. 

I can turn any liquid into any other liquid (like water into wine, acid into apple juice)

But to do so, you have to submerge your head into the first liquid for 1 minute for each fluid ounce you want to transform, rounded up.

I can turn any die I touch instantly into a Charlatan’s Die that I am automatically attuned to, which allow me to make the die roll whatever I want when I roll it

...but doing so your dice have sentience, being lawful good, who also has the ability to speak (in a booming voice and is understood by all humanoids), this dice has a 8 intelligence, 18 wisdom and a 15 charisma. This dice often asks"IS CHEATING REALLY HONORABLE, WITH THIS POWER TO AFFECT THE ROLLS?" and other remarks about you cheating.

(BTW  the dice has the mentality of a paladin)

I can turn invisible and become invisible as I choose, functioning as a greater invisibility spell, this excludes my retinas(so I can see)

But you can't turn back, also while you are invisible, you are just a pair of floating eyeballs, creepy.

I can cast the spell Goodberry in real life, at will, like a cantrip, this doesn't require any components besides vocal, which I get to pick the word(s) of when I cast it.