Go infinite by playing Augmented Elekk + Plot Twist when you have another Augmented Elekk and Plot Twist in hand. This will shuffle more minions into the deck to fuel the Darkest Hour combo. At 10 mana, Dollmaster Dorian can be played on the same turn to put out some small taunts and good deathrattles.
Play Rafaam's Scheme + Darkest Hour to summon up to seven minions from your deck. This can be followed up by a 1-cost Demonbolt. Note that if you pull either Augmented Elekk you will no longer be able to go infinite, unless it survives a turn and you have both Plot Twists and another Augmented Elekk in hand. It is likely that you will not be able to go infinite forever because of this, so Arch-Villain Rafaam can be used to spice things up a bit, but if he is pulled without an extra copy in hand or deck you will not be able to use his battlecry ever.
There is a fair amount of sustain between Zilliax, Rotten Applebaum, and Aranasi Broodmother. You can also Zilliax onto one of the mechs for more healing. I have included deathrattle taunts instead of bigger ones like witchwood grisly so that they still have some effect if cleared by a boardwipe.
The early game doesn’t look that great. We have low cost taunts which might be able to hold off aggro until hellfire, and are still not awful if summoned from the deck. The real problem this deck will face is bomb warrior, which will punish the use of Plot Twist heavily. To counter this one could play Arch-Villain Rafaam to destroy all the bombs and hope that the legendaries will win you the game.