Daemons, You Complete Me ...
Let's face it there are a lot of Pus-Heads (Nurgle fanboys) out there who have always wanted to run a serious Death Guard force and while the last dex let you mess around with lesser and greater Daemons, they never let you really get the whole deal. The allies chart let you add in daemons and it felt great, but adding already expensive stuff to a codex that has expensive stuff (CSM) doesn't really ever leave you feeling complete when making a good list. What the new book has opened up is the chance to flood the field with all manner of things Plague and Death Guardish, including Plaguebearers, zombies, plague marines, Great Unclean Ones (GUOs) and much more and do so with numbers and survivability.
Nurgle Daemons Are About Denial ...
While Khorne kills in combat, Slaanesh kills with combat plus shenanigans, Tzeentch shoots and buffs, what Nurgle does best is deny the enemy the kill by being shrouded with the ability to go to ground in many cases. Additionally, the Heralds, Great Unclean One and DPs have access to the Nurgle Powers (AP3 flamer, Nova T test ect) and also Biomancy, which has its own potentially outstanding benefits. What this amounts to is an army that can laugh off most shooting, while also being able to handle most non-dedicated close combat units in CC ... or at tarpit most things.
Form and Function of the Nurgle Allied Daemons at a Glance
When it comes to Chaos Space Marines, I think the cheap new price tag on plague bearers makes for welcome allies in a Nurgle themed list. On a board where there are ruins, or behind an aegis, Plague Bearers can post up on objectives and take 2+ cover all day and either through proper support or through massive numbers (huge squads), they can be pretty much guaranteed objectives. When it comes to objectives on your side of the board, I think bearers will function a lot like zombies or cultists, in a sense that they will be ignored in the early turns, but with the exception that they are more survivable than either, thanks to being able to go to ground (in the case of zombie comparison) and higher T (in the case of cultists). Keep in mind that they can also deep strike and that things like comm relays can help you make sure they come in when needed.
As an ally, I think the GUO is pretty good, being a High toughness MC with access to Mastery Level 3 and gifts, he can be a one-man death star, capable of deep striking into the back field and shaking off all but the most deadly fire and combat. He can use Nurgle powers to buff himself or debuff the opponent through biomancy OR use the Nurgle powers, which give him access to flamers and a Horde-destroying toughness-test Nova. This guy is the first batter up in my allied Nurgle list for testing. Beyond that you can grab a DP, which I will not cover because he isn't too attractive to me, or you can grab a Herald with gifts and FNP so you can add some defense/ offense to a big squad of bearers and call it a day.
Other units that are available for the allies lists are Soul Grinders, which are pretty beefy, though I think the anti-air autocannon is a lot like the flakk missile in the sense it really isn't too hot, but a AV13 deep striking walker with shrouding isn't too shabby. When I look at it as a potential opponent, I can see ANY grinder held in reserve as a potential counter to my Hell drakes, being able to DS in after the drake has hit the table and autocannon my back armor, which is situational, but still a valid threat.
Beasts of Nurgle are expensive and while I am inclined to say no to them as an ally, I can't help but wonder about them as they offer some potential charge defense to protect my back field units.
Plague Drones are another expensive unit, but they can help position units that I want to arrive from reserves through Icon use combined with their speed. They are also nice for hunting or tarpitting weaker shooting units that I need to silence to help out my CSM units.
How do My CSM Work with the Nurgle Daemons?
When it comes to the CSM side of a potential list, there is always Typhus (who may be a tad expensive for the GOU combination, though further testing will tell). There is always the Nurgle Biker Lord with the Black Mace, who in combination with Bikers or Spawn offers the list a durable unit that can reach out and touch someone. I will likely try both out. There are also Nurgle Sorcs or even plain sorcs if you want to break theme. Either one can offer utility to a list.
Zombies (for typhus) and Cultists are cheap troops that can basically hide in reserves to add scoring while freeing up points for big nasty stuff, while big squads can be used as Lord delivery systems, though I am still not quite sure about adding that stuff to a lord's price tag in terms of efficiency.
Plague Marines are always a nice choice and can certainly add a tough, scoring unit with good shooting potential.
I think Heldrakes are an obvious choice for any CSM list, but I think fit particularly well in a list that wants to hold objectives and deny them to opponents as they can really flame out troops choices easily, which combined with the ability of the rest of your army to hold objectives well, can win games.
Bikers, as mentioned above are great as are spawn. Both are good Lord delivery systems and Spawn are great for hunting down and crushing weaker units.
Nurgle Oblits are another great choice for a list that doesn't have much shooting as they offer flexibility in terms of deployment and weapons loadouts. They are also a good counter assault unit in a pinch.
Those are pretty much my wavetops, though I would overlook the Maulerfiend as a unit that adds close combat support and target saturation to the GUO, Havoks, who can lay down consistent firepower or terminators, who can also answer close combat support and close range shooting situations.
Straight Nurgle Daemons at a Glance
I think Nurgle Daemons are capable of functioning as a Mono-god list and in fact, I think they should hold up pretty well. Obvious threats will come from Dark Eldar, Guard cover denial shooting