Toying with a Jekyll/Hyde skin

I've had a "League of Extraordinary Teens" idea bouncing around in my head and have been playing with a new skin idea. 

Also having trouble deciding what skin Nemo should be (leaning towards Selkie)

But here is my draft of a Jekyll/Hyde skin...  It is somewhere between a werewolf and a ghoul.

You have always felt that you are more than what people perceive you to be.  They only look on the outside.  You know that what is inside of you has been waiting to break free, and now you have the means to make that happen.  This  formula has given you the ability to bring your inner self out, to take revenge on those who have slighted you.  And you know you can control it… can’t you?
Look
Plump, scrawny, average, disfigured
Hollow eyes, quiet eyes, calculating eyes, nervous eyes, murky eyes, cunning eyes

Origin
Accidental discovery, magical potion, family recipe, unusual allergy, careful experiment

Background
You have shared the recipe for your formula with someone.  Give them 2 strings, and take a string on them
Someone defended you from a smack down.  Give them one string.

Stats - -1 hot   1 cold   -1 volatile   1 dark


Moves
Take these two moves
+The monster released When you become your darkest self, roll dark instead of volatile to lash out.  You do +1 harm as well.
+ Immortality formula - You cannot die.  If you take 4 harm, you pass out and are helpless for (TBD) hrs.  When you wake up you will still have 1 harm.


Choose one more:
+ Versatile formula - choose a power from another book.  This power applies even when not darkest self.
+ Limited formula - you can only call the beast once per session due to the formula being hard to come by, but this means you relay on your mundane abilities more - you get a +1 to any stat. (if a move/situation would require you to become your darkest self aside from the 1 time, you do, but do not get the benefit of the “monster released” move in this circumstance).
+ You wouldn’t like me when I am angry - When you successfully hold steady (7 or up), you can also remove a condition (this move cannot be used to remove the terrified condition).  When you shut someone down, you gain a string on them (can result in 2 strings if you can choose a string as part of the base move)
+ The drug is the thing – Sometimes you see things, maybe they are hallucinations, or maybe you are seeing what is really there.  Roll dark.  On a 10 up, ask the MC three questions.  On a 7-9, ask one.  If you act on one of the MC’s answers, add 1 to your first roll, but subtract 1 from the next roll not related to these questions.
}} Which enemy is the most vulnerable to me?
}} What’s their secret weakness?
}} What poses the biggest threat to me?
}} Who’s in control here?
+ Feeling no pain – when you take harm, you can take the condition "On Drugs" and take 1 less harm.  As long as you have this condition, you take 1 less harm, but have a -1 to lash out physically.

Darkest self
You are a crazy killing machine.  You need to hold steady (7 up) in order to distinguish between friend and foe.  And once you are out of foes, you just don’t care who your friends are, only the thrill of the fight matters.
To escape your darkest self, you need one of the following
1) Take 4 harm (See immortality formula move)
2) As with ghoul (You escape your Darkest Self when someone restrains you or fends you off for long enough for you to regain your composure – at least thirty or forty minutes) or
3) kill an innocent

Sex move – when you have sex with someone, gain a string on each other.

I really like this skin, but there are a few "but"s:
First is the Immortal Elixir forced move. Having this as a forced move removes the players ability to actually die, or use death as a way to change skins. I'd prefer to remove it (you can always take the ghoul move that does essentially the same thing), make it optional, or simply rewrite it so that you change states, going from monster to human if you die and vice-versa.

The sex move is kinda boring. How about: "When you have sex, roll to hold steady or become your darkest self immediately. On 7-9, they gain a string on you. On 10, you gain a string on them".

First is the Immortal Elixir forced move. Having this as a forced move removes the players ability to actually die, or use death as a way to change skins. I'd prefer to remove it (you can always take the ghoul move that does essentially the same thing), make it optional, or simply rewrite it so that you change states, going from monster to human if you die and vice-versa.

That makes sense.  I was kind of thinking of it as a way to get him/her out of darkest self (though this skin has several already). It didn't really occur to me that players may want to die :)
Going from monster to human if you die, would have to maybe subtact one harm so they weren't just dead there...
If it was optional:
Kill me Twice, Shame on Me - if you are at 4 harm while your darkest self, you can immediately give a string to your opponent to revert back to your human form and heal (1 or 2, not sure which would be better) harm.  You can give your opponent a second string to immediately run away to safety.

This makes it different enough from the ghoul move they could ignore it, and take the ghoul one instead (thru versatile formula or an advancement). 

There is already an option to become your darkest self @4 harm which is in the base rules, so that works there too.

The sex move is kinda boring. How about: "When you have sex, roll to hold steady or become your darkest self immediately. On 7-9, they gain a string on you. On 10, you gain a string on them".

Yeah, I agree it is boring, it was one of the areas I hadn't really thought about it yet.  I like your option.  I like there being a "whoops" way to become darkest self for this kind of skin.

I was considering putting some kind of anger counter on the Hyde, where if you reach 5, you are forced into darkest self.  Of course, good role players will not need the mechanic, so why complicate it.

Not sure what the advancement track would look like either.  Most of them are standard, but not every skin has a "gang" option - would need to figure out if this one would or not.

I like my idea for a sex move too :-)
Just to clarify my thoughts behind it, the idea was that when you become emotional/hormonaly challenged/charged as you do during (good) sex, you have to roll whether to lose control, barely contain the bestial nature (which would make things arythmic and awkward, as you're focusing too much on selfcontrol), and controlling your "beast" completely, turning beastly lust to your advantage, thus gaining a string on your partner because it makes for damn good sex.

I like the Kill me twice, shame on me. Even the name is what I had in mind when writing down my thoughts, but it's damn hard when you have to do technical support over the phone while you write.

I like the idea of a Jekyll/Hyde skin.

I think the playbook is a little too "Hulk", making it be a little like Hulk is cool, but I want my Hyde to be more of a immoral lustfull sociopath and less of a berserker, which is truer to the source material / more interesting in Mosterhearts / less of the Werewolf all over again. In that regard I would rewrite the darkest self and maybe tweak a move or two.