Hearthpwn

How important is Arch-Villain Rafaam? Carftable or just not so important?

Not important. He's there because it's a huge taunt mainly. The ability is an extra bonus if needed.  Rotten Applebaum, Aranasi Broodmother, Zilliax,
Witchwood Grizzly, would be fine instead.

However I wouldn't recommand crafting specifically for decks arround and Plot Twist and Darkest Hour to climb the ladder. Unfortunately, I think these archetypes are too weak currently.

Hard to mix Plot Twist and Darkest Hour.

I've played this deck for about 20+ games, and I have too many tokens, and too few minions on Dorian+Plot. 

I've modified the deck and played a version where Darkest Hour is a secondary strat, with only 1 Darkest Hour, 1 Rafaam's Scheme and 1 Fiendish Circle. The combo is still good and fun, but less present.

Aranasi Broodmother is a mandatory card in a Plot Twist deck to help gaining health, so put the two of them in. Potentially, you can gain up to 2 times 4 health, times the number of times you draw them (standard draw + Plot Twist draw + some lifetaps); this is a lot of health, and you'll need it!

My win rate is around 60% with it, but unranked - we should tryhard the rank 20-10 ladder to see how it performs...

Update on ladder?

Did try out another Plot Twist deck, with out Darkest Hour.
Its a fun deck but hard at tempo decks, its works but you need the right cards... Going to try this deck out with some of ur changes.

Thx for trying and enjoying the deck ! I have actually tried with Aranasi Broodmother, which are usually present in the regular Plot Twist lists. Same for Rotten Applebaum. But I have had better results with Safeguard and Deranged Doctor instead. The Aranasi are better with Sense Demons which I don't run. And I prefer the 8/8 body of the doctor: the deck needs to be explosive when the Darkest Hour triggers, with big threats. And both token versions of the Safeguard and Deranged Doctor provide significant value when played by Dollmaster Dorian or Fel Lord Betrug. You can even reuse the Safeguard token 0/5 again as target for the second Darkest Hour.

There are many other lists with Plot Twist and Darkest Hour played separately. I have proposed this one because it's not common to play both. 
Regarding the ladder, I only managed to get arround max 40% WR at rank 10 .... As for many meme decks it struggles with crappy hands against aggro face decks.
However there are no real bad match up: the deck can manage huge come backs, because of the deathrattle which provide life and minions.
Maybe other ppl can get good WR with changes and good plays !

Mulligan: always keep one piece of combo. But not recommanded both at the same time against aggro.
Typically keeping Dollmaster Dorian and Darkest Hour in the same oppening hand is challenging.
Safer to go ether one or the other. Tokens can be played on curve just to stick board and divert. Until you can bring bigger menaces. For instance:
T4 Rafaam's Scheme or Fiendish Circle
T5 Voidwalker is an extra target for the Darkest Hour and can protect other tokens as well
T6 Darkest Hour
If you have early Dollmaster Dorian, and are not under pressure, draw as much as possible to get the biggest value from a
T7 Dollmaster Dorian and Plot Twist

You can play extra Twisting Nether against aggro; if you have managed a good Augmented Elekk with Plot Twist. Your deathrattle minions bring value while you clean the board.
If you control the game, keep drawing and put menaces.

Against aggro or tempo Rogue. Usually the opponent may not really know what you try to achieve. They tend to ignore the early tokens and go face without trading.
If you even manage to make a small 3 minions Darkest Hour, it could be enough to return the game in your favor.

Warr is definitely winable; especially with a max hand Plot Twist and Augmented Elekk. Then play your ressoures wisely arround AOE.
If you managed to create some token versions of Dr. Morrigan, it will definitley provide good value later.
Arch-Villain Rafaam with a big hand is another option in late game.

This deck is very unpredictable and fun to play; in many games your opponnent will make funny emotes "Wow" :-)

No ladder update yet, i'm strill trying a few variants of the deck... But it looks like mixing the both combos is not that efficient. Usually, I like having the tokens to tempo on T3/T4 to get to T5 where we have Zillax or Rotten Applebaum to continue towards later turns. But it's not always that obvious and the starting end is not as stable as with aggro decks... So often, you get a bad game because of a bad draw and mulligan...

In longer games I've manage to beat some fatigue warriors because the deck is actually very resourceful when you manage to get to T7+. Lots of health to pass the midgame and dry the resources of most aggros decks. I still think there's something to do with it... Will comment if I've got something new...