WarlockGame isn't out yet so this is purely a guess on what will be strong, although I did play (briefly) at a press event and this setup did seem to be a standout. Will update this as time goes on.
This build will be using the 
Dread Claws core skill which seems to be ridiculously strong right out of the gate, providing insane damage, low resource cost, tons of synergies, and it happens to look sick as hell. We use the Encircling Terror Dread Claws node enabling the skill to be performed in a circle around our character providing great AoE coverage in addition to more damage via proccing an additional cast when paired with a greater demon. 
Summon Taz'Rauth counts as a greater demon, and provides a massive damage increase for us. I'm unsure if it's necessary, but for now it seems good to have another greater demon summon for 100% uptime on the additional cast we get, which we'll achieve with 
Rampage 
Nether Step is purely for mobility, Early we'll use 
Hellion Sting as our basic skill for supplemental single target damage with Eviscerate Hellion Sting, later we'll swap to 
Command Fallen I'm mainly using this for 
Fallen Rush Command Fallen because in theory it means you don't have to manually press your basic skill in order to generate wrath to spam cast Dread Claws however I haven't tried it, so it's possible in practice 
Doom ends up being better.
For our last skill we'll opt for an ultimate, either in the form of 
Terror Demon Metamorphosis or 
Terror Swarm. I won't know which I think is better until I play, they both have the exact same uptime, however Terror Swarm just passively does a lot of damage, while Terror Demon Metamorphosis massively buffs your Dread Claws. However, these variants of the ultimate aren't unlocked until level 41, so until then we'll be using 
Sigil of Subversion for hex application and some movement speed here and there. I may swap this at some point, 
Doomfire Ritual Doom might unironically be better for the purposes of applying hex, at least on single targets.
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