First few things that stand out to me include your Warriors squads being too large to fit into the Ghost Arks, Anrakyr doesn't seem to fit into this list, and I'm curious why you chose Particle Shredder's for your Stalkers.
I would go ahead and split up your Warriors into more units. I like having nice large squad to walk the table between Ghost Arks and keep the Ghost Arks full with their own squads.
Why no Immortals in an Anrakyr list? One squad get free special rules and are a little sturdier to hold an objective.
The Triarch Stalkers don't need to bring more Anti-Infantry to the table IMO. You already have 65(130 rapid fire!) Gauss Flayer shots on the table, plus the Destroyers for MEQ, and the Doomsday Arks for TEQ (or anything for that matter.) Personally I don't see the point in spending any extra points to change the guns out on the Stalker. The standard Heat Ray is great and versatile with a Flamer template or multi-shot Melta.
The only problem I have with the Doomsday Ark is it has to stay still to fill holes in the list. Once it moves it's just another anti infantry weapon, and it has to move to gain the Jink save. Plus the gun sits so low to the ground that basically any cover gets in the way so you need the best firing lines, and that usually involves moving to get them throughout the game.
I noticed I'm a little late to help out before the big game but if this is the list you used, let us know how it went!
Sorry for the late reply, but it's been a busy weekend.
You are correct that the warriors are too numerous to stay in the arks. I am still a fan of the old phalanx of ours, and am seeing if I can get it to work with a large number of warriors advancing together with the arks repairing the fallen, and doing emergency pick up in case of too many casualties. I have used a similar list with CSM with two 20 man squads of marines hiding behind a moving wall of two rhinos as they advance across the field.
Anrakyr doesn't really fit in the list, though I'm not sure what kind of list he really would fit in. I personally enjoy the gimmick of playing with your opponents toys, making a vehicle blow up a squad of its allies before being glanced to death. I'll experiment with him more, but will most likely swap him for a better suited support lord as follows.
Overlord - Warscythe, Weave, Res Orb
Better support for a blob of warriors, and a bit cheaper. Plus I won't be relying on gimmicks.
About the Stalkers. I took a decent amount of time considering the weapon options. The heat ray is a pretty decent weapon, however, it isn't that hard to miss those two shots. Also, I'm not worried about the AP, I'm used to Necrons not having it available to them before, and the Doomsday Arks have TEQ covered for the most part. The cannon is too expensive for what it offers in my opinion. Most of my army is 24" threat range, so the cannon lighting up a target outside of that is relatively useless to me. However, a large blast autocannon? Yes please. Oh dear glorious chaos gods please. It is pretty cheap, pretty powerful, and automatically hits what it touches.
I agree that the Doomsday Ark has limitations, however you can still pull some advantages from them. Even if your firing lanes leave some room for cover saves, then you can use this to control your opponent's forces. He will most likely keep more of his army behind the cover, while still taking a lot of saves, which helps you move the rest of your army into a better position. Also, it gives your Doomsday Ark the same benefit of cover. If the opponent steps out into the open, then those blasts will be punishing.
Alright, onto my thoughts after the big fight. First thing is I had to change my list a bit last second, but for the most part it stayed the same.
Anrakyr the Traveller
Triarch Stalker - Shredder
Triarch Stalker - Shredder
7 Scarab bases
Tomb Spyder - Fabricator Claw
My opponent played a footslogging world eaters list with Angron, and a land raider with a group of termies inside. I'll try to avoid a battle report, and just give my developing opinion on my units in the fight.
Anrakyr didnt' really get to do anything fancy considering there was only one enemy vehicle, and it immobilized itself on a puddle in the enemy's deployment zone.
Warriors and Ghost Arks - Well, that was a fun blob of death. I was fortunate on a mysterious pond that had an objective in it. The pond turned out to give feel no pain to the unit inside. So 15 warriors, with 3 saves a piece, with an Ark behind them to bring more back proved more than the Khorne Flakes could handle.
Stalkers - I actually really enjoyed using the shredders. Anytime a squad that got close has to make a handful of saves, which ended up killing about the same as the heat ray would have done. Handing out free twin linked weapons to the other units really made the army much more impressive in the shooting phase (Deathmarks?) I'm going to keep playing with the shredder for awhile.
The Deathmarks were one of my favorite units, and they were a last minute decision to build instead of Immortals. They finished off Angron, and started rending the squad of terminators before being over run. I know a lot of lists are abusing the cryptek with the low ap template, but I'd rather make good use of the range on their weapons from cover, and becoming even more potent when enemies try to get too close.
The Tomb Spyder was dead weight this game. My vehicles either exploded, or weren't scratched. All with the exception of a Ghost Ark that caught itself on a tree on the last turn of the game.
Doomsday Arks were definitely a good time. They were in the corner of the board with clear view of most of the battlefield. Other than the large ruins in the center. They vanquished many of the Berzerkers that got too close to my army. The only had to move once during the game to get a better LoS on the opponent's deployment zone in order to keep lobbing particles on his objectives.
In the end, I really enjoyed the core of this list. The force had a fair amount of synergy. However, there was a few units that didn't really do their part. Those being Anrakyr, the Scarabs, and the Tomb Spyder. If I were to change Lords, and drop the other two, then I would have 175 points to play with. That could buy me more warriors, a third Doomsday Ark, or heck a larger group of tomb spyders.
My apologies for such a long wall of text, but I do realize this seems a bit against our current meta, so I'm up for some reading. Anywho, thanks for the input thus far.