Blizzard revealed nearly all the Hero Talent Trees with the launch of the War Within Alpha and subsequent builds.
Our Demonology Warlock guide writer, Not, offers an early review of the Soul Harvester Hero Talents that offer a consistent way to AoE with strong spec integration.
Initially the overall tree has a theme that is fairly tied into damage over time and more linked in that way to Affliction, however there are parts of the Soul Harvester tree that give it a twinge of Demonology flavour in such a way that you are able to play around Soul Anathema similar to how you play around with the Dragonflight S3/4 tier bonus' Doom Brand effect, juggling the DoT across multiple targets activated through consuming Demonic Core which triggers Quietus and Sataiel's Ambition which can loop further and trigger Shared Fate/Feast of Souls. This kind of feedback loop through static gameplay, while not super interactive is fun to see in action and can be especially potent in dungeon/open world situations where you can (or are) chain pulling mobs onto one another creating massive Soul Flame-esque explosions akin to Legion Affliction.
Keystone: Demonic Soul
Generally speaking, compared to Diabolist, this keystone is much more passive and brings in a lot of Soul Shard generation by way of reducing the cost for Hand of Gul'dan. The Demonic Soul itself is a Sha-like entity that