This post has taken me a little longer than usual, this is because it's a bumper edition, as Typhus brings with him a parade of units to talk about. Hence the long title. But I'd better dive in as this is going to take long enough without an introduction.
Plague Marines are coming up first. As you'd expect, they are the toughest of the cult troops. T5, Feel No Pain, Fearless, etc. So I'm going to open this up with how well they do as troops. With your backfield, objective grabbing units you want 2 things. Durability, and a relatively low points cost. The durability to ensure that they don't get knocked off the board and the points cost because they aren't going to be involved with the main fight most of the time due to other priorities and you want as few points tied up in this as possible.
This can often be tough to balance. So, how would Plague Marines do it. Stock 5 man squad, boom. 5 Plague Marines in cover are going to be a little daunting for your opponent to shift, especially with all of your other goodness stomping across the field at them. Therefore, you don't need to pour almost 25pts more per model into making the unit slightly more durable, as it will end up becoming hideously expensive.
Plasma Pistols, don't bother, far too expensive, despite the fact that it's extremely unlikely that a Plague Marine will die from it overheating. Flamer, Meltagun, short ranged story, Plasma, maybe, a little expensive for something that is probably only going to be getting 1 shot all of the time, although you can move around, so long as you can be sure of getting to the objective in time for turn 5.
Leave the Champion alone, he's decent in a challenge anyway with his T5 plus it's such an unlikely scenario that it's not worth pouring into it. Plus Blight Grenades are excellent anyway as it can really blunt your opponent's charge, giving you the upper hand in the inevitable challenge.
Icon of Despair, Fear is a terrible power, it's not worth committing more points into it. Veterans of the Long War is also a no, as although you will become more useful at dish out out damage, that's not their primary purpose, and it could often tempt you into committing them when you shouldn't.
So going forward, how are they? Well they aren't going to dish out too much damage, but they can be an excellent tarpit. T5, Fearless and FNP make them very difficult to kill but removing all charge bonuses from your enemy unit really helps. The best way to deal with them really is to shoot them, but your opponent only has so much shooting.
The only other downside is that they're not particularly fast, like spawn are, so your opponent has the opportunity to simply avoid them. Which then leads you to the question of why not just take Spawn? They're faster, more durable, cheaper and will probably dish out a decent amount of damage too. Plague Marines get 2 attacks due to their dual close combat weapons, but at the end of the day they don't penetrate armour. Granted it's 4+ poisened, but it's still not fantastic unless you pour a ton of points in there to get a lot of attacks.
Out of all of the God specific marines, I would say that Plague Marines are the best, they're good at holding back on objectives and they're not terrible pushing forward, but we still don't have an excellent Troops choice.
The second Troops choice that Typhus offers us is the conversion of your Cultists to Plague Zombies. Essentially, as you'd expect, a cross between Plague Marines and Cultists. This gives your Cultists Feel No Pain, Fearless, Slow and Purposeful and reduces them to only having 1 close combat weapon.
Yes they may not churn out much damage but when you have over 200 of them on the board then you're going to be causing some damage. Unfortunately they do not stack with Epidemius, as they don't have Mark of Nurgle, however, they are so cheap that you can afford to sling in some toys such as some backline shooty units such as Obliterators or Havocs, or maybe a Heldrake. I probably wouldn't use Spawn in conjunction with Zombies as a) their movement will be severely restricted by all of the Zombies in the way and b) all of your Zombies are excellent tarpits anyway. Zombies are a great Troops choice, as they're cheap and extremely durable, with Fearless being the kicker there.
That said, the best use for them is probably with other squads of Zombies, as a single squad on its own doesn't make much sense to me. Sure they may be good for holding backfield objectives but you're not making full use of Typhus, plus if you're taking Zombies they're your best Troops choice anyway so why would you take any other.
The main thing that I've learnt from playing against Typhus is not to put him in the middle of a squad when there's a Manticore around (lots of hits, you're going to fail some look out sirs and if you fail a save the Manticore has made its points back and then some). But this is internet punditry! There is no room for experience here!
Typhus is a close combat machine, granted his Warlord Trait is a little underwhelming and he'll have to eat your sergeant more often than not before doing any real damage whilst hoping not to turn into a Spawn or Daemon Prince in the process, but once he gets to the meat of your squad he will smash through it.
Starting small, he has Vets of the Long War, Hatred marines, although this doesn't matter too much given the context it's always nice. He has a pretty monstrous statline, T5 as you'd expect, hitting pretty much everything on 3s and 3 attacks. I5 and W4 were a nice surprise, although the Initiative bonus doesn't make much of a difference unless facing a guy with Jaws.
Onto his special goodness though, he is armed with what is essentially a Force Axe, with 2 notable changes. Firstly, it grants +2 strength, and secondly, it is a Daemon Weapon, granting him a boatload of extra attacks, and this is what makes him monstrous. Anything that is able to hurt him, like Power Fists and their equivalents, aren't going to be striking until he is, and that is enough as he is going to tear things up.
He also has a couple of other boons. He is a level 2 psyker, which I like for the improved Deny the Witch more than anything else as it makes him even more durable, and he has another special rule called the Destroyer Hive, which is a large blast centred on Typhus in combat causing a Bolter hit with an AP of 2 against models under it. With ignores cover just to clarify. Ouch.
So, Typhus is a close combat monster, and he unlocks an excellent Troops choice and another good Troops choice. But how to get him into combat. Well, there are a couple of options. The first is Land Raider (notice this is a recurring theme), the second, which I've seen used quite often is to slap him inside a squad of Plague Marines who walk him to the other side of the board. To be honest I might be tempted to put him in a squad of regular Chaos Marines instead, with an additional close combat weapon and Mark of Nurgle. It'll make a cheaper alternative and they'll do the job. Plus Typhus gives them Fearless anyway to stop them running off.
In conclusion, this post should be positive enough to break the recent string of negativity, for their points the conclusion is this. Plague Marines, Ok – Good. Plague Zombies, Very Good. Typhus, Good.