I think the number of appealing Elites choices in all codices from CSM onward can be counted on one hand. Lessee... Riptides... Um... Crisis Suits, but they're usually troops. Ironclad Dreadnoughts? Well, I've never seen one, so I guess not... Wow... Fire Dragons! Okay, two-and-a-half!
So I guess this time I'll talk about why you don't like your elite choices, and we'll throw in Cypher for the hell of it.
Terminators
I run them for fun from time to time because they are, indeed, pretty fun. However, Terminators, despite having 2+ armor, are very vulnerable to dakka, which is in ample supply. On top of this, they are vulnerable to anything with AP2. And this, too is in ample supply. Since the cost per model is so high, you get less firepower for the points, with little extra durability. They are an assault unit that is slow and cannot sweep, so if they win combat and break the foe, they get away, and you're left standing there waiting for the shooting.. If they win combat and wipe the foe, they are left standing there waiting for the shooting. If they lose combat, they might get swept, or get away and be left waiting for the shooting.
If they do get to assault, as long as it isn't something like a horde of Hormagaunts, they should be in solid shape. The trick is getting there, and that means a Land Raider, usually.
I have five Termies. I painted them up like Thousand Sons and usually run them with three combi-meltas, MoT, a chainfist, a heavy flamer and power mauls so they can conceivably threaten just about anything. They have yet to pull their weight, but I run them for giggles nonetheless.
Like Abaddon, the best you can hope for is to wipe one unit with them and then be left footslogging it in search of distant targets that got out of Dodge while the gettin' was good.
Mutilators
Mutilators got better in 7th. I proxied some Nurgle Mutilators in a Land Raider once in 6th and sent them charging at a Tyrannofex because what else are you going to charge them at in a Tyranid army? In 6th, that thing could smash them with two attacks per turn, but he missed a lot and I rolled all but one of my saves and actually killed the thing and got them into another scrap.
Nowadays, MC's can't smash but once. Yay! Oh, wait a minute, boo! That's why Mutilators are slightly better, btw.
The annoying thing about these guys is they can't use power fists. You can switch between chainfist and power axe/maul/sword or lightning claw, so you'd better wreck that walker on the charge or it's your ass. And for dudes who have so completely devoted themselves to mastering melee combat, one marvels why they are still WS4 after millenia of practice.
I see them more as vehicle poppers than unit killers. They haven't the attacks to bring down swarms, can't sweep, and fear power fists, but they can threaten Imperial Knights and Land Raiders and walkers and tanks. In this regard, I think the Mark of Tzeentch might be more useful for them than for Nurgle in order to help them tank those S10 or D hits they'll be taking against such targets.
Yet in the end, you're going to put them into a Land Raider, drive them up to a target, hope they kill it, and then they will do nothing else with them for the rest of the game because that is the nature of small footslogging assault units, hence the reason nobody takes them.
Helbrutes
On their own, they are underwhelming since they are too slow to get across the board, and their firepower doesn't measure up to what real shooty armies can bring. Chaos wins by rushing across the board and charging clowns who think assault is dead. To that end, the formations help out some. I've tried the Helcult and found it underwhelming as fearless Cultists still die very fast and become totally ineffective below 15 models or so.
The Helfist Murderpack is slow, but hard to remove, and could be interesting alongside a trio of Soul Grinders, but I'll never try it out myself. Bonus points if you can get invisibility or forewarning on the squadron. How I would kit out such a squadron would depend a whole lot on what I supported it with. I don't want that unit tarpitted by Zombies or Termagants trying to swing their way clear with two measly attacks per turn. So maybe heavy flamers and missile launchers all around? 5 D3 heavy flamer hits on any swarm that wants to charge them and five frag missiles to thin them out while still being able to threaten light mech. Honestly, I haven't given it a lot of thought, but if you wanted to run this, you definitely should before you build the squadron.
The Mayhem Pack is probably the best way to run these since you get to deep strike them where they need to go, and that's how the army is supposed to work. Again, if I were to build this formation, I'd have to think long and hard about what I supported it with before I picked the weapons for the models. I see merit to two heavy flamers and two powerfists. I also see merit to the multi-melta/powerfist/heavy flamer build. I think I'd pick that one. The big gotcha is the always crazed thing can hose you from time to time, possibly denying you the critical charge.
The bummer is, the formations take up your ally slot in most major tournament formats, which is a rule intended to save us from ourselves.
Cypher
I forgot to include him in the HQ review so I threw him in here since we're short on subjects. I've run him once with 20 CSM's. It was meh. Hit and run kicks ass. Shrouding kicks ass. Infiltrating Spawn or Bikers into ruins is cool, and probably the best thing to do with him. What isn't cool is his 190 point price tag, which is breathtaking.
Is Cypher worth more than a Soul Grinder or five Nurgle Spawn, both of which are cheaper? I really can't say at this point. Missions these days are shifting more towards an emphasis on mobility. Chaos depends on throwing as much as you can at your opponent to reach assault and Cypher deprives you of a unit with which to put pressure on the opponent. He does, however, provide a lot of durability to that one unit. Ruins will be everywhere in this edition, and Nurgle Spawn with 2+ cover are happy Spawn. Also, they are angry Spawn.
I do someday want to try him with a big squad of Slaanesh Bikers led by a Daemonheart Lord with the Icon of Excess, because 2+ cover/5+ FNP is almost as beefy as a Seer Council with no psychic Hail Marys to deal with, and that squad will cause havoc all over the board. This might be the first thing I try after BAO. My Relictor Bikers will have to throw in with Chaos for that game, but there will be some nasty business coming for the other guy.