As you can see I finished the Triumverate and the Deathworld Forest kit. As a painting project I found them models challenging in the way that they're layered, and in some ways they're easier to paint before being put together than when they're done, but the final product is striking on the table top. As far as the Forest, I opted for bright colours for most of the build as it is a stronger contrast to my army. I may even go back and add some further detail work on the terrain if I get bored enough, but even completing the main roots and trunks without picking out the fungi with a different colour than the rest of the trunk they look great. If the vines didn't cover the giant runes on the Eldritch Ruins you could probably get away without painting those if you wanted to (though I chose to paint them).
Having used the Deathworld Forest in a game we decided that if you were in overlapping areas that you had to take the effects of both pieces of terrain, which means in some areas you were taking AP 3 wounds on a 1-3. Over the course of a game the Deathworld Forest managed to kill 2 of my Scythe-Wraithguard, wounded a Wraithknight and took out both a Jetbike AND a Warlock (with sanctuary and Fortune). It was pretty harsh for me. My opponent, on the other hand, suffered a total of 0 wounds. While the 3+ save was handy (or a 2+ for the Nightfight turn) I'm not sure it balanced out the sheer destructiveness it unleashed upon me. This is definitely NOT to be confused with army friendly terrain such as the Tau wall or any of the slew of imperial stuff. That said it does look pretty.
Recently I got to play an 8k game against a Castellans of the Imperium force that included Guilliman as its warlord. We also tried out the Empyric Storm cards and the Balewind Vortex rules we'd come up with (the rules can be found here). While I did try out some new formations like the Ulthwe Strike Force and Triumverate, the game was big enough for me to include old favourites such as Crimson Death, Aspect Host, Wraith Host, and Seer Council. I added in a small cad as a complement and I was ready to set the world alight.
Things I learned:
The Visarch is better than I'd anticipated. Lacking an invul and being... not quite enough of a beat stick in my eyes I didn't have much in the way of high hopes, but the warlord trait that works when he's not the warlord was pretty useful, and since I had him in a small unit of Incubi it became clear to me that it was a substantially good way to deploy him. He took the first two wounds in the squad and then, as other models in his unit died, he'd regain a wound and gain an attack. I maxed him to the +3 attacks pretty quickly, but with Rage he really shines in a small unit taking on a greater foe.
The Revenant Discipline doesn't tickle my fancy. For me the best spell is the one that triggers a soulburst at 24" and all the others are forgettable.
Harlequins feel so much more formidable as Ynnari. The ability to pull off charges in an early phase, do some damage in an assault in the wrong phase, and then Hit & Run, followed by another charge in the same turn makes even a small squad a bit of a nightmare for opponents.
Wraith blades feel more viable with Strength from Death. Cannon and Scythe guard, however, feel too good. I paired up 10 standard wraithguard with an Archon with portal and when they entered play they were effectively guaranteed to trigger themselves for a soulburst. This meant the moment they drop down they wipe out two priority targets, assuming I place them correctly. That doesn't even include how likely it is for the scythe guard to self trigger. I had average luck with the heavy wraithcannons, but the Suncannon firing effectively 3 times every turn was an unholy terror on the board. I could see people using that build again once they see how effective it can be.
Strength from Death seems to move the game forward at an insane speed, making time to play the game all the way through exponentially quicker based on the game size. It really is an amazing defence against drop pod armies as they can lose units that haven't even fired yet to either assault or return fire. In some cases I was able to do more damage to my opponent in his turn than he was to me. We called the game after 2 1/2 turns when he had somewhere between 700 and 1500 pts left and I had roughly 6,500 pts left. I had roughly run through the equivalent of 5 turns of shooting in that time. It was absolutely ludicrous. Playing against Ynnari will require completely different tactics than playing against any other force in the game. One thing to recognise is that once the force gets rolling it's an absolutely juggernaut. In many ways if you're caught off guard it doesn't just feel like you're playing against a new army... It feels like the two players are playing different games.
The Ulthwe Strike Force is interesting, but my predilection for large units means I actually find Battle Focus more helpful to the unit than Strength from Death.
I really, really want to try Shining Spears out in the Ynnari list. I think they are one of the units that is potentially terrifying.