INFINITE Demons! "Never-ending Hell" Warlock

Alright, here's the breakdown:

Finish the quest as soon as possible. Archmage Vargoth plays two very specific roles in this deck. On turn six, you ideally want to play Vargoth followed by Plot Twist. If you didn't draw Vargoth but managed to complete the quest already, the other use for Vargoth is for duplication, which will be discussed later on.
Get as many copies of Sathrovarr as you can. One of the ways you can do this is by playing Expired Merchant. If you play Expired Merchant against classes that can silence, bounce, or steal it; be sure you can also destroy it on the same turn with a card like Unstable Felbolt.
Another card you want destroyed is Kanrethad Ebonlocke. You'll want Kanrethad Prime in hand right before you complete the quest.
Once you finish the quest and have a bunch of Sathrovarrs shuffled into the deck, play Lorekeeper Polkelt, and use the hero power.
From here, you can either duplicate Sathrovarr by playing Vargoth in combination with Felosophy, or you can play Felosophy without Vargoth, play Kanrethad Prime, and copy the Prime with Sathrovarr. To go infinite, you'll need to copy Sathrovarr too and make sure that after each subsequent turn, you have at least one discounted Sathrovarr in hand to copy. If you don't need that much value, however, just keep copying the Kanrethads.

There's also a couple of other different ways to approach this deck depending on the matchup.

Against decks that lack hard removal like Druid, copying a fully discounted Flesh Giant with your two Sathrovarrs should be enough pressure.
Against naturally aggressive decks, you can choose to copy your Aranasi Broodmothers and shuffle them into the deck with your Plot Twists for much needed healing in addition to gaining plenty of Taunts to protect your face.

Legend has it that the Felosopher's Stone can convert Wild decks into Standard decks. For those of you who missed Bloodreaver Gul'dan and Cubelock, here you go.

-BloodEclipse