Fun new meme OTK with Octosari, which requires a bit of setup.

Play Octosari and Dalaran Librarian, kill Octosari

Trade Wicked Shipment to summon at least 4 imps.

Then, reduce mana cost of the combo cards to 10 or less mana, either by Runed Mithril Rod or The Dark Portal:

Void Virtuoso

Power Overwhelming

Rain of Fire

Devourer of Souls

Treachery

Tamsin’s Phylactery

Tamsin Roame

Wicked Shipment

When you are ready, play Void Virtuoso, Tamsin Roame, Devourer of Souls, Power Overwhelming on Devourer of Souls, Wicked Shipment, Tamsin’s Phylactery x 2 (from Tamsin), Rain of Fire, Treachery on Devourer of Souls for the OTK.

This combo draws a lot of cards for both you and the opponent and takes equally long time to finish, so settle in.