Urien Mill + Hypex/Uber Grot/Plg Squad

Baleful is very much the obvious replacement for Fearmonger, who I think may be a little expensive as another disruption mechanism when it could be another win-battle condition, yes, very valid. I will see how he goes.

Possessed is always going to be a much more known entity, as well as a much greater deterrent from committing to whatever planet it's at for your opponent. Generally I want them to have as little information as late as possible. I like the Plague Squad because I can functionally change its ATK value constantly, including with the cards I'm using to trigger Hypex (or with Fearmonger even if somehow my hand were not what it should be). It may be one dollar's difference but that dollar is a big deal postdeploy phase, or even in it, as more choke - a Power from pain or a Razorwings - which is not only going to disrupt their counter-strategy but extend your combat capabilities in the form of boosting VPS or triggering Uber Grotesque or Hypex.

With decks in general I want to be cautious and scheme (the appeal of Urien) rather than robotically pilot a collection of good stuff (I have a Shadowsun deck and a Sicarius deck that just play themselves), thus the desire to decentralize my game away from what's actually sitting at the planets.

I tried to make Fearmongers work.  They don't feel like they justify their price.  Compared to Warp Spiders who have a similar stat line and arguably a similar ability  Fearmongers fall short.  I find Warp Spiders ability is actually more useful to keep the denial game going.  Ultimately Spiders cost one less resource.  I feel like Seer Of Deceit is a better three cost include if you are taking chaos as an ally.  That way you can boost your own draw engine to up the consistency of seeing key cards.  Seer is also a solid combat unit.  In contrast Fearmongers are really only useful as a slow hand milling tool.

VPS sounds like it has synergy in this deck where you are discarding all their good units, but he suffers from just being inferior to Possessed.  If you swap in Possessed I think you'll find your combat game will be way more consistent.  Note Possessed can have wargear attachments so they fill that Uber Grot slot you were going for as well.

Coliseum Fighters sound good on paper, but with so few units and no promotions I think that slot would be better served filled by a Void Pirate or Chaos Fanatic.  With the current unit spread I'd think you'll have a tough time locking down command to solidify the choke game, which is really what make's Urien with Crucible work.  As is you are just relying on the combo of Hypex and tons of Tortures, which can work but feels like it will be very inconsistent.  Since this deck relies so heavily on that combo I think it would be greatly served by adding more draw acceleration.

Add: The successful Hypex decks I've seen try and capitalize on the ranged phase thus locking out non range units from participating in the combat.  With these units they'll ready with high attack value but they will most likely be the target priority for your opponent so I'm not sure how many Hypex activations you'll get on average considering you'll need to throw away some of your events as shields to keep these guys around.