I played against this list and found it extremely effective.
I do see where
CrownAxe is coming from -- but are not wyverns super cheap? What else could those points be spent on? When I played with
WitnessMe4Khorne, his wyverns were very effective, but against a riptide/stormsurge wing list they would be a lot less useful. So the question is, where is the point of diminishing returns. How many opponents are bringing enough infantry to make them worth it -- and how big of a hit is it when you can't use them?
I was at the same tourney as
WitnessMe4Khorne, and the wyverns would have been useful in 2 out of 3 of my games. In one of those games, 3 wyverns would have done the job as well as 6.
I've not been a fan of meltabombs in the past, and I think they can be taken off the bikes to free up more points.
Is there a way you can give some more weapons to the command squad to give them more teeth. In our game the chimera was kept in the back line and seemed just a 'tax'. Is there a way that could be made to a 'counter punch' unit. I know in
IG lists, you can use a vet squad with 3
PGs, which is a bit deturring. Is there something you can do there?
Are 37 plague zombies to much? Could 30 do the job just as well to free up a few points if you need.
The laser destroyer batteries were money. 75% chance of hitting with
STR 9. That's honestly why I still think Phelgm is overkill. The torrent is cheaper and still gives some good punch. That combined with your melta bikes, khorne dogs, and soulgrinders makes me think you have enough anti-armor.
I'm also a big fan of Tzeentch on the grinders. Rerolling 1's to save adds up, and the better the save of the grinders, the better the save gets. If it's night fighting, and your ginder is sitting in a ruin, the ability to reroll ones gets extremely high! Even with just a +1 save on the grinders, it increases the save from 50% to 58.33% damage reduction.
~6000
~2000 
1000pts Space Marines 
1200pts Tau 
2500pts Blood Angels 
3500pts Imperial Guard/Renegades 
and 1700pts Daemons 