Zoolock remains one of the strongest archetypes in Hearthstone to this very day. Its new iteration involves several new Demon cards from The Boomsday Project like Void Analyst, Doubling Imp, and Nethersoul Buster.
The new buff spell, Soul Infusion, also gives a huge advantage to an already well-established deck increasing its power level quite significantly. Nethersoul Buster works especially well with Kobold Librarian, Flame Imp, and Vulgar Homunculus, which can quickly turn it into a 3/5 or 4/5 for only three mana.
The rest of the pack are your usual suspects, such as Voidwalker, Knife Juggler, and Doomguard. It feels like this deck will never die, but will always change and adapt to the current meta.