What is the basic element of the Deathwing force? The Terminator squad. As such, it would probably do us well to figure out how to use them. I mean, the whole point of running terminator-heavy out of the Dark Angels codex is to run these guys as troops.
I won't lie; this is a themed build so it's going to accept some limitations. At any rate, on to the building block.
The Deathwing Squad
The Deathwing squad costs 215 points, and gets us 5 fearless terminators.
Terminator Armor has a 2+ armor save, a 5+ invulnerable, grants Relentless, and disallows sweeping advances. Terminators carry a BS4 Storm bolter, which is adequate for anti-personnel work with two S4, AP5 shots. In assault, the basic Terminator carries a WS4 powerfist. S8, no armor saves, I1? The only downside is I1. However, Sarge carries a power weapon, so you at least get a couple S4, I4 swings that ignore armor saves.
Ranged Weapon Options
Each Deathwing squad may choose one of the following:
-Heavy Flamer (S5, AP4, Template) [5pts]
-Assault Cannon (S6, AP4, 24", Heavy 4 Rending) [30pts]
-Cyclone Missile Launcher (S8, AP3, 48", Heavy 1) [20pts]
The burnination device and assault cannon replace the storm bolter, whereas the Cyclone sits on the back and lets you fire it and the storm bolter at the same time.
Looking at the list, on foot your best option is pretty much the assault cannon. The Cyclone just doesn't do a ton against armor; a single S8 shot just kind of falls short of being impressive. Alas for the lack of the GOOD Cyclone launcher statline. The heavy flamer is hard to bring to bear if you're walking. If you're going to teleport, well, if you can land on target then the flamer's more of an option. The Assault Cannon's shorter-ranged, but it can consistently wound just about anything with a toughness, it rends, and it can be adequate against light-to-medium armor.
Melee Weapon Options
You have three melee weapon options with a Deathwing Squad
-Replace a powerfist with a chain fist [5pts]
-Trade your ranged kit for a pair of lightning claws
-Trade your ranged kit for a Thunder Hammer and Storm Shield
For a mere 5 points, just about every squad should take at least one of these. Five points, the ability to mug higher armor-values? Take it.
The melee weapon options bear a bit more thought. To be honest, the Thunder Hammer and the '4++ only in melee' storm shield fall a bit short of being useful. About the only real reason that comes to mind is for wound-allocation purposes. The Lightning Claws...the benefit is that they're more effective in melee than a power weapon, and they have I4. You do, though, lose the Storm Bolter.
The downside of the melee weapons? If the enemy has power weapons, you're getting a 5+ save. Not so great, considering a given terminator is about 43 points. You have to try to pick your fistfights carefully, and if you run into vanilla-dex TH/SS termies? Not a good day for you, since you fight each other about equally until you make saves. Then his 3+ beats your 5+ hands-down.
The Use of the Deathwing Squad
To be honest, if the strength of your army is Terminators as troops, it's probably a good idea to bring heaps of 'em. Why?
Terminators have one transport option: the Land Raider chassis. It's the same cost as the squad, and it also cuts down the number of troops you have on the table in two ways: 1) fewer points spent on terminators, and 2) one less squad physically walking on the table.
As such, I think walking them is a good idea. A Raider with a squad and heavy flamer + chain fist is almost 500 points, which means that the best you could do is 3 of them and Belial in about 2,000 points, along with maybe some spare change in points.
The other problem with Land Raiders is that if the enemy DOES bring specialist kit to kill them (and a good one will), then you've not got a lot of stuff on the table.
As such, we'll be walking with guns. Assaulting them would be a fine idea, save that you have to get there. I would suggest the following configuration for the basic squad:
Walking Deathwing Squad
Sergeant w/ Power Sword
Pro: all distinct models. Hellooo, wound allocation shenanigans. If you want to skip the lightning claws, you can. This little bit's actually fairly comparable to a dakka-pred, save that it can monkey-punch vehicles to death. If you feel the need for a second chainfist, hand it off to the Assault Cannon, so they can't both be outed in one group.
You're capable at shooting, nastier at melee, but must carefully pick your fights and avoid power weapons like the plague. That's just how it is for Deathwing Termiantors.
Riding a Land Raider Crusader
4x Lightning Claw Pairs
1x Chainfist/Heavy Flamer
3x Lightning Claws
1x Chainfist/Heavy Flamer
1x Storm Bolter/Chainfist
If you're rolling out of a crusader, you're going to assault. As I've said before, I'm not so hot on the idea of 3x Crusaders. 2 of them, in higher points, maybe. Still, this is what you'd toss out of them. Use lightning claws, your initiative, and perhaps a chaplain for the re-rolls. Heavy flamer helps you thin the numbers, as even with massed lightning claws you're not THAT killy. (16 swings = 8/12 hits depending on WS, 6-10 wounds) If the enemy doesn't have power weapons, you're fine.
Supporting the Deathwing Squad
Here comes the tougher part, or the part that differentiates the Deathwing army: how do you back the boys in white up? They're adequate for anti-infantry work with guns, and can threaten light armor. They're not exactly long-ranged, though they can reach 30" in a turn with a move and shoot. At 1850-2000, you're probably talking 15-25 terminators, or 3-5 squads.
So, what's that leave you needing?
-Longer ranged power.
Oh. And remember: POWER WEAPONS KILL YOU BADLY. If the enemy has a lot of them? Might very well be game for you. It's honestly one of the weaknesses of the army. I mean, Doom + a squad of Howling Banshees is NOT your friend.
We'll cover that another time. Feedback welcomed.