Guide to Space Marines
The Angels of Death
SpoilerCombat Squads: This rule is quite strong, provided that you use it correctly.
1. This version of Fear isn't actually totally terrible. Read your opponent's list; If Fear works, keep it. If it wont, re-roll.
2. Furious Charge is kind of lame.
3. Anything that makes your Warlord more survivable is worth getting.
4. So strong.
5. Not great. Space Marines have And They Shall Know No Fear, so Morale checks aren't a big deal.
6. This is arguably worse than the above, since there are certain situations where failing a Morale check is actually advantageous - especially coupled with ATSKNF.
Pretty bad table. Roll Strategic instead.
Your 'Chapter' is defined by which Chapter Tactics that you use. Just noting that if you have a model in a unit with a different Chapter Tactics to another model in the unit, the unit benefits from neither Tactica, which is in total opposition to established fluff of Marines from different Chapters being able to learn from each other, but, that's not important - RAW is Law.
Allies: You can take an Allied Detachment from your own Codex, but only so long as they have a different set of Chapter Tactics to your Primary Detachment. Why would you do that? We just went over a rule that hamstrings you for doing so! But, you can fully take Dark Angels, Blood Angels and Space Wolves as Allies with no downsides, since those versions of Space Marines don't have Chapter Tactics, and therefore don't screw you around. So...Yeah. What a terrible rule.
Various Detachments give you Combat Doctrines. Each rule that gives you access to Combat Doctrines is cumulative.
Tactical: Re-rolls To Hit in Shooting and Assault Phase. Strongest Doctrine. Especially when it applies to Independent Characters that join Tactical Squads.
Assault: Re-rolls in the Assault Phase only - lame. A lot worse than the Tactical Doctrine, since the Tactical Doctrine does the main part of the Assault Doctrine, and the Tactical Doctrine makes the most important Phase of the game (Shooting) even stronger.
Devastator: Shooting Phase only. Which instantly makes it better than the Assault Doctrine.
The Gladius Detachment consists of 1-2 Battle Demi-Companies, and one or more other Detachments from the Codex. It's okay, since it gives Chapters who aren't Ultramarines access to Combat Doctrines, which is okay, because re-rolls To Hit are always welcome no matter what you're doing, and, for Gladii that are Ultramarines, it's even stronger, since now you have six uses of Doctrines - or, rather, x2 Tactical and Devastator. The Company Support of aspect of a Gladius seems to have people divided; You must take what amounts to a Company of Marines, and, in return, you get free Dedicated Transports. Unfortunately, at minimum strength squads (which is the only feasible way to do it), you're just handing your opponent free Kill Points for games where that matters, and there's some dead weight in the Detachment where you could be spending points on other things, that really matter. If you don't already have the ~11 Transports ready to go, don't go building this Detachment.
A major problem for some, is that the Gladius Detachment doesn't have a Lord of War slot. Yes, you can take Calgar independently, but you don't have a provisional slot for a Fellblade, Typhon (when it isn't banned) or Cerberus, which immediately makes the Gladius weak in certain metas.
Primarch's Wrath: AP4 is nice. Salvo 5 is also pretty great. Bring a Bike or Terminator Armour so it actually matters.
Teeth of Terra: Fun, but pointless.
The Shield Eternal: There is no reason at all not to take it every time.
The Burning Blade: It's not strong. Always bring a Storm Shield if you want to use it.
The Armour Indomitus: What a waste of 60 Points! Don't bother. Just take Terminator Armour for a whole lot cheaper. 'Artificer Armour & Storm Shield' is half the points. Seriously. What is GW even thinking!?
SpoilerCaptain: Artificer Armour, Power Axe, Melta Bombs, Shield Eternal (+/- Auspex). Done. Taking a Bike is strongly recommended, since the aim of any Captain be to not just replicate a Unique Character that already exists. If you have the points, it's also recommended to upgrade the 'Power Axe & Melta Bombs' to a Power Fist or Thunder Hammer, but, if you're going to spend that many points on one model, it's strongly recommended that you also have Grav-weapons in your army (or even in the Captain's own unit) to throw Concussive at your opponents' units so you actually get to use the items that you paid so many points for. If you have the points, upgrading to...
Company Master: ...is even better, because the extra Wound is very good on a model that has Eternal Warrior, and if you're going to have a Company Master with Shield Eternal, put them on a Bike. It's just a good idea in the first place, and, with the Bike you're no longer just trying to replicate Captain Lysander. While an Orbital Strike has a special 'Shoot and Charge' rule, what it doesn't change, is the standard Ordnance rule, that says that you can't 'Move and Shoot', to that end, its a really good idea to have a Bike or Terminator Armour, for access to Relentless, or be accompanied by Centurions for Slow & Purposeful.
Librarian: Go with a Stave or Sword, normally. Since unlike Captains, a Librarian doesn't get Artificer Armour or a natural Iron Halo. Armour Indomitus is trap. Melta Bombs are generally a good idea, and an Auspex is just helpful. If you want to take Terminator Armour & Storm Shield, then you take the Unwieldy Axe. Anyway, Biomancy is good in general. Divination is great for Shooting, Telepathy is great for Assault. The usual.
Techmarine: Like a Librarian. But you trade the Psychic Hood, Psychic Powers and Force Weapon for a Power Axe, 2+ Armour, an AP1 Power Fist and Bolster Defences. They can try and fix Vehicles, but generally that doesn't work. Not worth it - especially if you plan on taking a Thunderfire Cannon, which you should.
Chaplain: Zealot is reasonably strong if you plan on Charging. A Chaplain is locked to a Power Maul, or a Power Fist, and can't take any other weapons (inb4; The Burning Blade...No.), but, Melta Bombs are cheaper than a Power Fist, and a Power Fist is a Specialist Weapon, so you lose an attack on your Power Maul. Don't take unless you have to.
SpoilerTactical Squad: A Marine. Power Armour and Boltgun. But they don't matter. What you're really after is the Special and Heavy Weapons. Meltaguns and Plasma Guns are generally the go-to staples. But in certain metas full of Monstrous Creatures, Grav-Guns and surpass the Plasma Gun simply because of the Concussive rule, that shafts Monstrous Creatures to I1, while your Marines can hit it first with Krak Grenades. Heavy Weapons, as a rule, typically aren't seen on Tactical Marines, mostly because the literal best Transport for them, is the amazing Drop Pod, which means that Heavy weapons are going to end up shooting Snap Shots and generally, being a waste of points, while the Squad's Special Weapon and the Sergeant's Combi-Weapon do all the work. Speaking of Sergeants, just don't bother giving them Melee weapons. It's not worth it, they've only got one Wound, and die too quickly. Related, don't bother making them Veteran Sergeants, either.
Rhinos just aren't strong. Razorbacks should only be taken as part of the Gladius Strike Force so you get them for free.
Scout Squad: In broad strokes, 3+ Armour doesn't matter. The 0.16 fraction difference it makes against small arms fire makes little-as-no difference. If your Tactical Squads aren't in Drop Pods, spewing Melta, Plasma or Grav fire into your opponent's lines, then you're much better off with Scouts, which give you early-game board control. Especially against opposing Deep Strikers. Boltguns are going to be the best option you can give your Scouts. Infiltrating is not optional, which means you can't Charge on the first turn. Either you're going to get Charged, in which case you want to Overwatch, or, you're going to have the first turn, in which case you want to unload as much fire into your opponent as possible - that's Boltguns.
Sniper Rifles; You need lots of them - at least two units' worth - before they start making a difference.
Shotguns vs. Combat Blades: The attacks are S4, AP-. Normal Melee attacks don't have an AP value. But, if you're within 12", you can shoot your Shotguns, go for it, two attacks, identical to your Melee attacks, which hit on 3+ (BS4), and then you can Charge, for an extra 2 attacks (S4, AP-), for a total of 4 attacks. If you have a Bolt Pistol, you shoot one shot, at AP5, sure, but one attack per model, then, luck willing, you can Charge for an extra three attacks (S4, AP-) per model. But, with dice rolls being the same, it's always possible to fail a charge (and/or get Overwatched), in which case you just lose those attacks. Then you have to factor in that Weapon Skill, being useless, is more than likely to hit on a 4+.
Shotguns; 2 Attacks (S4, AP-) hitting on 3+, and 2 Attacks (S4, AP-) hitting on whatever WS your opponent lets you.
Bolt Pistols; 1 Attack (S4, AP5), hitting on 3+, and 3 Attacks (S4, AP-) hitting on whatever WS your opponent lets you.
Remembering that you can fail a Charge, or get Overwatched, in which case you just lose those secondary attacks.
(BT) Crusader Squad: The special unit for Black Templars, they can take a minimum 70 Point 'Tactical Squad' and take a Heavy and Special Weapon for a minimum investment. Basically, this means Missile Launcher/Lascannon and Plasma Gun. Weirdly, Black Templars actually make the best Parking Lot army, that is, if Parking Lots weren't dead. If you want to make a Melee squad, you can throw in a Meltagun, and Power Axe, and then, unlike Tactical Marines, a Power Weapon on your Character model might actually be worth it, here. Since with the extra Power Axe, you can actually do things, since the only Melee-capable model in a Crusader Squad isn't the Character model, and then you can pick up Neophytes with Shotguns, which are ever so slightly better than Combat Blades.
Last; Objective Secured Land Raiders. Don't bring a Land Raider unless you're bringing three.
SpoilerCommand Squad: A staple of any 'Death Star' list you want to make, since there happens to be a single model that gives everyone in the unit FNP; The Apothecary. Always bring one, he's efficient and makes sure that your super squad doesn't die. All of the Standards are pretty lame, so don't bother. The Company Champion would be great if his only weapon wasn't AP3, but, as it is, he must take Challenges, even when an attached Independent Character more than likely has an AP2 weapon and can win the Challenge - don't take the Champion unless you have to, which you don't. Bikes are phenomenal, especially when you add FNP which you are. Melta Bombs are handy to have, and make sure to bring some 3 Storm Shields. There's nothing wrong with fast-moving Melta weapons, but, if your Command Squad is being accompanied by an IC with an Unwieldy weapon, throwing Grav-Guns (especially on Bikes for Relentless) into the unit is never wrong, since Concussive. Ultimately, the Command Squad is a very effective Ranged unit, that can Assault if necessary, usually due to the presence of one or more Independent Characters.
Honour Guard: A unit of 2+ Armour and Power Weapons. No Invulnerables. No FNP. A Champion must Issue and Accept Challenges (it's okay 'cause he can bring a Thunder Hammer). No Ranged weapons - Boltguns don't count - and no access to Melta Bombs. Quite lame, really. Considering that they're supposed to be the Chapter's finest warriors. If you're going to take them, you're going to need at least 7 of them, because your opponent will shoot them, and they don't have Invulnerables or FNP and they will die - 2+ Armour on its own just isn't that good. Anyway, you have no reason at all to drop your Boltguns. Yes, it's slightly harder to model, but that doesn't matter. Relic Baldes aren't worth it at all. Any model that you think needs a Relic Blade, can be given a Power Axe instead, for free. Throw in one, maybe two Power Mauls, and leave the rest as Swords. While it sounds cool to give the entire unit Axes; Between getting shot at, and going last in Melee, it's not worth it. Just mix your weapons so you get some attacks in. Even though rolling Swords against 2+ Armour sucks, it's better than rolling no dice at all.
Don't bring a Land Raider unless you're bringing three. Otherwise, Drop Pod.
Centurion Assault Squad: Three in a Drop Pod with Twin-Linked Meltaguns each. There are no other options. You've got an extra seat left in said Drop Pod, for an IC. Slow & Purposeful is passed to the Chapter Master, who can fire his Orbital the turn he comes out of the Drop Pod.
Vanguard Veterans: Can re-roll their Charge range, and that doesn't suck. Power Weapon + Storm Shield + Jump Pack = 37 Points per model, and that's not bad at all. Honour Guard get 2+ Saves, and that's great. But Vanguard have Invulnerables and can move faster, and re-roll Charges. Throw in some Power Fists/Melta Bombs as needed, and you've got a unit that is a lot better than Terminators. While Vanguard are more expensive than Honour Guard, Honour Guard can take a Chapter Banner which evens out the points some, so it's a wash. Vanguard can Jump though, and re-roll Charges, which means that they're very fast. Strictly speaking, they don't benefit from Chapter Tactics (Raven Guard) because they're already doing it, but, they're still a strong Melee unit, and all Melee units benefit from Shroud & Stealth. Take a lot of models, or don't bother.
Sternguard Veterans: Never take Storm Bolters - ever! Don't bother with Combi-Flamers, you already have Special Issue Ammunition that does what Flamers do. The only Heavy Weapon worth taking is the Heavy Flamer, since you can't get it anywhere else, and paying 150 Points for Sternguard (x5) with two Lascannons is complete trash, when Devastators (x5) for 150 Points have four Lascannons. Some people might try and convince you that Heavy Bolters pair well with SIA - they're wrong. Even if you're running a 'line' squad of Sternguard outside a Drop Pod, they're still better off using those 10 Points you paid for the Heavy Bolter on a Combi-Plasma or -Grav. They're an entire unit of Combi-Weapons and sometimes Heavy Flamers. Point them at any unit you want and it'll probably die, with the exception of Gargantuans. But, even against Gargantuans, Sternguard can deal not-insignificant damage.
Dreadnought: AV12 isn't good. An AV12 Walker is even worse. If you're going to take any, you want to take them in Squadrons.
Venerable Dreadnought: Ditto. But still slightly better than the above, so maybe you only need two instead of three. Lascannon, Missile Launcher combo, or dual Autocannons.
Ironclad Dreadnought: AV13 is good. Move Through Cover with Grenades is strong. Heavy Flamers are the meta. If you're going to be taking any Dreadnoughts at all, Ironclads are far and away the best Dreadnought chassis, due to the fact that they just have AV13 and the others don't.
Legion of the Damned: No Chapter Tactics. Generally speaking, not one of the strongest choices in the Elites section, despite all their stock rules. They always start the game in Reserve, and you shouldn't have those kinds of units in your army because you're Space Marines with Drop Pods. Their big selling point is Slow & Purposeful, coupled with Ignores Cover on all their ranged attacks. Plasma- or Melta-spam, go! They're fairly good at taking out a single target. But, Sternguard can do that, too, in a Drop Pod, benefitting from Chapter Tactics. Never take Flamers.
Terminator Squad: Always bring a Chainfist. The Terminator Sergeant is locked into a Power Sword, and that's bad. Heavy Flamers, Assault Cannons and Cyclone Missile Launchers are all good options, pick your favourite depending on what you want them to do. Five Terminators fit inside a Drop Pod. That's all.
Terminator Assault Squad: Just swap everything to a Thunder Hammer and Storm Shield. Leave one with Lightning Claws - not the Sergeant. Drop Pod. However, recall that five Terminators takes all the space, and you don't have IC support off the bat. So, if you do plan on 'Podding in Terminators (that goes for the above unit, too), you want to make sure that you've got more than one threat on the board that your opponent needs to deal with. Why not take two Terminator Squads? Why not take 3 Centurions & IC in a Drop Pod? Point is, don't hinge your battle plan on 5 models that don't have support. Terminators are not a Star Unit. You're thinking of a Command Squad.
SpoilerAssault Squad: Always take Flamers. Always take Eviscerators. Melta Bombs on the Sergeant. That was easy.
Scout Bike Squad: A cheap way to put a Locator Beacon on the board before Turn 1. Cluster Mines are a cute trick, but not worth 20 Points. Take as many Grenade Launchers as you can. Some say that the 'minimum size' unit of Scout Bikes is 4. They're not wrong per se, but, if your goal is just to have a cheap Locator Beacon on the board for your Drop Pods, spending more points than you have to on something that becomes useless after Turn 1, probably isn't the greatest idea.
Bike Squad: These should just read 'Troops'. You should never, ever be taking these as straight Fast Attack. For 7 points per model, upgrade all your Tactical Marines to 'Bike' unit type, and make their Boltguns Twin-Linked, and lose squad size restrictions on Special Weapons. Basically, if your Tactical Marines aren't in a Drop Pod, they should be on Bikes. Tactical Marines on foot, are just outclassed. The 'Heavy Weapon' for Bikes is always a Multi-Melta, if you choose to have one.
Attack Bike Squad: Unless Kor'sarro is your Warlord, just no. Put them in your Bike Squads, and make 'em Troops. On some level of Hell, you may be tempted to run Heavy Bolters with Chapter Tactics (Imperial Fists).
Land Speeder Storm: Even at AV10, it still manages to be one of the best Transports in the game. It Scouts, which is cool. It functions as a 12" bubble of board control with its Jamming Beacon, and shoots S4, Large Blast Blind Grenades, and it's a Skimmer so it can Jink. It's only 'problem' is that it only Transports Scouts...Which isn't a problem at all because Scouts are great. Which is fine, because a 'Storm should always be a Dedicated Transport, so it has Objective Secured, so your opponent has to get rid of it (that is, if he's not already sick of rolling Blind checks all day). Always pick up the Heavy Flamer, it's free and good. If you're thinking about putting a Multi-Melta on your Land Speeder Storm, you should probably throw your army list in the bin and start again. Melta weapons can be taken anywhere else, while Heavy Flamers are only on a limited selection of units.
Land Speeder: Pretty bad. If you compound your mistake, and buy three of them, you get to move an extra 6" in the Shooting Phase instead of shooting. If you do take three Land Speeders, it's probably not for the extra Flat Out boost. The Devil's Advocate says that maybe Land Speeders can be used to grab Objectives in the last turn, but that assumes that an AV10, 2HP Vehicle has survived 'til the end of the game.
Rhino: Not strong. Serves as a weapon platform for the squad inside, where the Rhino only buys an extra unit's worth of shooting for the squad inside. Anything that you put in a Rhino, is probably better off in a Drop Pod. If the unit is carting Heavy Weapons, still don't use a Rhino...
Razorback: ...and take a Razorback instead. It's another gun. Still just as weak defensively as a Rhino, except will use its Smoke Launchers even less.
Drop Pod: If you're reading this far, you've seen the words 'Drop Pod' appear 24 times, there's a reason for that - because they're good! Half of them automatically show up at the start of Turn 1, anywhere on the board, and they don't explode to bad Scatters. Drop Pods are the reason for the existence of Scout Bikes in any list that matters, although you certainly don't need Scout Bikes for Drop Pods to be effective.
Stormtalon: One of the better Fliers in the game, due to the fact that it's cheap, and shoots a bunch of shots with Strafing Run. Skyhammer Missile Launcher is easily the best option, and not just because it's cheap.
SpoilerDevastators: If your Tactical Marines are in Drop Pods, you probably don't want to waste points giving them Heavy Weapons, those points should end up here, unless you have a better idea. Missile Launchers are generally the best option, with a couple of Flakk Missiles in for good measure. At 35 points per model, Grav-Cannons are way over-priced...Unless you have a serious infestation of Flying Monstrous Creatures and Gargantuans.
Centurion Devastators: In nearly all cases, take Grav-Cannons. The only reason not to take Grav-Cannons (and take Lascannons instead) is if you're Imperial Fists, and you're not escorting an IC with an Unwieldy weapon. Omniscopes are basically mandatory, and it's nice to have a set of Missile Launchers for the range, and that's it. Grav-Cannons.
Thunderfire Cannon: A good choice for most armies. You get a Techmarine that trades his Power Axe and the Independent Character rule for the TfC. This is worth it. You still get Bolster Defenses.
Predators: Lascannon Sponsons, keep the Autocannon turret. That's it. AV13 is what makes this Tank barely useable.
Whirlwinds: If you have a Squadron of 3, they're viable... Then your opponent destroys one AV11 Tank and now the other two suck. Waste of ~200 Points.
Vindicators: Take three if you want. Even when they're reduced to a two model Squadron, they're still S10, AP2 Large Blast. Always pick up a five point Storm Bolter, that way a Weapon Destroyed result only has a 50% chance to brick your Tank, instead of 100%. Remember that with AV13(+1), it's always handy to remember that you can Ram and/or Tank Shock, just in case you do get bricked - known as The Nokia Maneuver.
Hunters: Fun, but bad. Because...
Stalkers: ...Exist. Shoot two Flying targets with 3 shots each, or fire at one, Twin-Linked. Very good. If you were thinking of kitting all your Devastators with Flakk Missiles, don't, and just take a pair of Stalkers. Take three Stalkers and now you ignore Jink. But, even removing one model down to two in the Squadron, you're still Stalkers, and you're still arguably the best Flier defense that Space Marines have (Stormtalons are good, but they don't start on the board like Flying Monstrous Creatures can).
Stormraven: It's 200 Points, plus the models inside, and it all starts in Reserve. If it doesn't arrive on Turn 2, that's a sizable chunk of your army that's gone missing. Still, if you don't use it's Transport Capacity, it's actually a fairly solid Flier at AV12. Always take the Twin-Linked Multi-Melta. When resolving Skies of Fury, remember that Ironclad Dreadnoughts have Move Through Cover, and other Dreadnoughts don't.
Land Raider: It has Lascannons.
Land Raider Crusader: Always take a Multi-Melta. Only take a Crusader if you need the Transport Capacity - or are a Crusader Squad.
Land Raider Redeemer: Better than a Crusader, in regards to being a Tank that kills things. Always bring a Multi-Melta.
SpoilerBattle Demi-Company: Half a Company, and you don't even need to take max squad sizes. Everything in the Formation - all of it - has Objective Secured, and you get a single use of the Tactical Doctrine for the Formation. A single Battle Demi-Company is quite strong. However, if you want to take one, you should probably take it as part of a Gladius Detachment, and take the cheapest Auxiliary tax you can think of, and then you get all of the Combat Doctrines, and Tactical Doctrine (the best one) twice!
Anti-Air Defense Force: 2+ Stalkers and 1+ Hunter. Hunters are not strong at all, and you're far better off spending Hunter points on more Stalkers. BS5 Twin-Linked is good, but the Hunter has to hit first, and if it doesn't, you get nothing. Spend five more points to upgrade the Hunter to a Stalker, and give all your Stalkers Ignores Cover. But, wont your opponent just destroy the third Stalker, and then you lose Squadron benefit? Yes. But how is that different from your opponent destroying the Hunter?
Stalkers are good. Hunters are not.
1st Company Task Force: You actually have to read your opponent's army list, because you nominate before Deployment. If you aren't already in the habit of reading your opponent's army, this Formation will start making you do it. Pick your opponent's best unit, and gain Preferred Enemy against it. This is one of those 'Ally Formations' that you throw into another army (i.e; Astra Militarum, Sororitas), where that army can gain 3+ units of Fearless, Fear-causing Space Marines in their line. In the Marine meta, Preferred Enemy is a great way for Sternguard to avoid the downside of Vengeance Rounds, without Librarian/Divination support to get Prescience.
Anyway, bottom line, if you're using a Space Marine CAD, don't use this Formation unless your Elite slots are already being used. If you want to Ally in Space Marines to your existing non-Space Marine army, this Formation is great. The only downside to the latter, is that you can't take independent Drop Pods for the Terminators to ride in.
Strike Force Ultra: Replaces the Formation from the Dataslate of the same name. If you really, really love Terminators; Ignore this Formation, and take a 1st Company Task Force.
Reclusiam Command Squad: Would be good if the Chaplain threw out a Fearless aura. Unfortunately, he throws out a Hatred aura instead. Since the Chaplain is over-costed at 90 Points anyway, you could take the Standard of the Emperor Ascendent on the Command Squad for 60 Points, a Storm Shield on the model, is another 10 Points, and then you could take a Power Weapon or Plasma Gun for 15 Points. Remembering that you have to take the Command Squad anyway, so the comparison works. The only benefit that the Chaplain brings, is that it's another model. But, you have to pay the tax of the Razorback, which isn't an Assault Vehicle, and basically useless for a Formation of this type. Terrible.
10th Company Task Force: Another 'Ally Formation'. If you're already playing with Space Marines, you're much better off giving them Objective Secured, and playing with them as part of your normal Detachments. It's great for Space Marine armies who just want to take 3 units of Scout Bikes, but, you must pay the 20 point Cluster Mine tax per unit to get your Twin-Linked Precision Shots, which isn't the best. Still, the 10th Company isn't weak, especially as the minimum 3 Scout Squads = 165 Points, is the minimum you need to pay to turn your Battle Demi-Company into part of a Gladius Detachment, where everything in the Gladius has Objective Secured anyway, so you should have more than enough ObSec with a Demi-Company & 10th CTF, which gives your Scouts access to Tactical Doctrine (if you aren't already Ultramarines, say, Raven Guard), which allows them to re-roll 1s To Hit, which can turn into Precision Shots if you're lucky.
Important; Camo Cloaks does not grant Stealth, they give a bonus similar to Stealth, which stacks with Stealth, and Shroud. So Raven Guard are really, really strong in this Formation. Even if they aren't allowed to take Telion, and also; Scout redeployment isn't a Move.
Storm Wing: While the 10th Company Strike Force might be the cheapest way to turn your Battle Demi-Company into a Gladius, a Storm Wing is the best. Since you get Fliers, which can actually hurt FMCs, which all of your Tactical and Devastator Marines are carting Boltguns and can't hurt anything worth a damn because in order to be able to field the BDC in a reasonable points limit, you had to skimp out on a bunch of wargear. Anyway, unless you are running the Gladius, there really isn't any need to field this Formation.
Centurion Siegebreaker Cohort: Centurion Assault Squads are pretty bad. Building Hunters (?) should rarely come into play, and when it does, don't you already have multiple units' worth of Meltaguns? Are you that unlucky? Anyway, a very weak Formation, because Centurion Assault Squads are already weak to begin with, and the Command Benefits aren't good enough to warrant buying boxes of Centurions and not kitting them as Devastators.
Land Raider Spearhead: Your Land Raiders become Super-Heavy and can ignore the Damage Table (except for Explodes!), and then re-roll Armour Pen and To Wound against big stuff. Supposedly, this is supposed to bridge the gap, where the Gladius Strike Force doesn't have true Lord of War slots. In any case, any Land Raider in the Formation that isn't the Godhammer variant (that's the one with the Lascannons) is largely a waste. At the end of the day, it's 750 Points worth of pseudo-Super Heavies, where you could take two Imperial Knights, instead.
Librarius Conclave: Strongest Formation in the book by far. All Librarians can take Terminator Armour, all of them can take a Storm Shield if you want them to. Very, very solid Formation for a minimum investment of 300 Points (although you probably want to invest slightly more).
Armoured Task Force: You'll need a lot of Tanks. To get the most out of the Formation, you really want to get Squadron bonuses, which means a minimum of 9 Tanks. It's very strong if you can field 'Vindicators (x3); Storm Bolter - 375 Points' x3 = 1125 Points, plus Techmarine. Takes roughly 1250 Points, and then you fill up the rest of your army with Scouts or Tactical Squads in Drop Pods, just to put more threats - and ObSec - on the board. Unfortunately, nine Vindicators costs as many as nine Vindicators, and you'll need to hit up eBay to field the Formation if you don't want to hate yourself.
Suppression Force: Just No.