Editing Warhammer 40,000/10th Edition Tactics/Space Marines (section)

===Infantry===
*'''Assault Squad:''' Space marines with chainswords, ideal for deep-striking from a drop pod if you want to fail a bunch of charges, or for charging them out of a Land Raider. While you can support them with some special weapons, the central focus remains on those standard chainswords (and not any eviscerators you pick up). Any time this unit fights, their chainswords get to pick between '''Sustained Hits 1''', '''Lethal Hits''', and '''Lance'''. Naturally, a Lieutenant can help make your job that much easier by making you pick between only two buffs each time they fight.
**Note: the following rules are optimal based on what you wound on:
*** Wound on 6+ (T8+): '''Lethal Hits'''
*** Wound on 5+ (T5-7): '''Lethal Hits''' or '''Lance'''
*** Wound on 4+ (T4): '''Lance'''
*** Wound on 3+ (T3): '''Sustained Hits 1''' or '''Lance'''
*** Wound on 2+ (T1-2): '''Sustained Hits 1'''
**'''Jump Packs:''' While they aren't nearly as focused on their chainswords, their jump packs make them more mobile and Hammer of Wrath makes anyone they charge suffer MWs for each 4+ you roll. Combined with a Chaplain, you can make units explode before you even fight them.
*'''Vanguard Veteran Squad:''' ''Scouts 6"'' make them more mobile than you'd expect, but they remain the dedicated melee force you need. Each one has S5 AP-1 heirloom blades as standard issue and charging adds ''Lethal Hits'' as a bonus. As such, a Lieutenant isn't strictly needed unless you're planning on protracted fights. A Chaplain or Librarian, however, can give you some good support.  If you don't modify their weapons, they're an Assault Squad ''but worse'', so strongly consider storm shields pr hand flamers for everyone.
**'''Jump packs:''' Replaces ''Scouts 6"'' with the jump pack's speed boost and deep-striking capabilities but otherwise remain identical. Any heroes with jump packs do a lot better for them with some really needed perks.  As with the bare-back squad, strongly consider hand flamers or storm shields.
*'''Command Squad:''' The retinue of choice for any firstborn heroes that aren't going all-in with something else. Sadly, they're stuck at five models - two veterans who can pick up any weapons you need, an Apothecary to bring them back from the dead, an Ancient to give them OC2, and a Champion with his souped-up ''Precision'' power sword that gives +1 to charge and advance rolls as well as unlimited free uses of Heroic Intervention. 
*'''Devastator Squad:''' Has a bunch of weapon choices, but for ''most'' of them you're better off with some other unit.  What's really unique to this unit is how cheaply you can spam grav-cannons on bodies that only take up 1 spot in a Drop Pod, so you should probably consider doing it.
*'''Scout Squad:''' While flimsier with only a 4+ save (but now with W2), they can always deploy smokescreens and have ''Infiltrators'' to arrive wherever they want.
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''Scouts 6"'' let them arrive within mid-range, which is where they need to be. Between their shotguns and bolters, they can have decent range and as long as nobody's within 6" at the end of the opponent's turn, they can immediately run back into reserves. If you're not as inclined to keep always moving, you can grab a missile launcher or heavy bolter for some heavy firepower.
*While you can replace the team's bolters with knives, this only gives them a single attack over their basic CCWs. Don't expect to use this on anything above GEQs.
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Not nearly as mobile, but they have ''Stealth'' and a squad-level equivalent of ''Lone Operative'' for additional protection. While their sniper rifles aren't quite as powerful as the Eliminator's rifles, they are far better protected. Even better, you can grab a missile launcher so you can also hit tanks as well. The one issue is that you will need them to move once the enemy gets too close.
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*'''Suppressor Squad:''' The Zaku-esque autocannon squad is notably the only Primaris Squad without ''Phobos'', ''Tacticus'', or ''Gravis''. Like Eliminators they remain stuck at 3-man unit sizes, and only have an okay-ish anti-MEQ gun and a hit roll debuff for targets hit by said gun to show for it. Fans of Autocannons will find better performance on Firestrikes, Predators, and Invictors.
*'''Astartes Servitors:''' Four walking meatshields for your Techmarines with T4 4+/6++. That said, they need that techie to keep them at their best with a bonus to WS and BS. Hell, there's no reason (aside from points and losing '''Lone Operative''') not to take them as they can join alongside another retinue for the Techmarine, allowing you to strap some servo-arms and heavy weapons onto a squad that'd need it. Don't feel guilty about losing them either, as they're all OC0 and thus don't really care about battle-shock.

====Tacticus====
*'''Bladeguard Veteran Squad:''' The retinue of choice if you need a walking bunker. At W3 3+/4++ save they're not quite as tanky as last edition had them, but every Fight phase lets them either re-roll 1s on their invulns or re-roll 1s to hit so you have a choice on either going all-in on the offense or getting extra protection.
*'''Desolation Squad:''' The Liefeld-Pattern Launcher Lads somehow got more oppressive with their indirect launchers, [[Imperial Guard|since remaining stationary grants them ''Ignores Cover'' AND cancels the hit penalty for indirect fire]]. Adding to that, the changes to ''Blast'' make the respective weapons more reliable against basically all unit sizes, with bigger of course remaining better. Plonk 'em somewhere safe and rain bullshit upon your foes.
*'''Hellblaster Squad:''' Like with any squad rocking ''Hazardous'' weapons, their optimal ride has a big Firing Deck so they can shoot, kill their ride, disembark, and shoot again - and that's ''extra'' true for Hellblasters, because their 3+ shoot after dying rule will work on disembarkation deaths just fine.  If they live through disembarking but die from the second round of shooting, you get to roll for a ''third'' round of shooting.
*'''Infernus Squad:'''  Equipped with AP0 heavy flamers (or S5 flamers, if you prefer). They also get the ability ''Purge the Foe'', causing one {{W40kKeyword|infantry}} unit that got flamed to make a Battle-Shock test. Got the specialized role of clearing out GEQ units and forcing Battle-Shocks. Still, they're no faster than any other foot soldier and they've only got a 12" non-assault weapon, so transport is often recommended. Remember that Overwatch can now happen in the movement phase, which means your opponent really doesn't want to end a move within 12" of these.  Fundamentally the '''Tacticus''' version of Flamer Aggressors.
*'''Sternguard Veteran Squad:''' Equipped with impressive A2 AP-1 bolt rifles with ''Assault'', ''Heavy'', ''Devastating Wounds'', and ''Rapid Fire 1''  all at once, so they can easily threaten anything in any position. If you're feeling particularly stupid, any of them can swap this for a nearly universally worse Combi-Weapon (1 less shot at all ranges at a relative -1/-2 when standing still/-infinity when advancing to hit in exchange for wounding and penetrating ''only infantry'' more easily).  1 in 5 can upgrade to a Heavy Bolter, which has functionally the same accuracy (losing 1 BS and gaining '''Sustained Hits 1''', which is a wash) and rate of fire at all ranges (3, but can't fire when advancing) but has +1S and more importantly +1D.  They have Bolter Drills, a single-use ability to shoot twice in the same turn right after destroying a unit.

====Phobos====
*'''Eliminator Squad:''' Dedicated snipers, complete with ''Infiltrators'' and the ability to add ''Devastating Wounds'' if they sit still on top of ''Heavy''. The bolt snipers will do more than enough for you, giving decent damage and ''Precision'' to pick out any key enemies, while the las fusils give you something just to total small vehicles and below. The sergeant can instead pick up a bolt carbine, a visible downgrade as a weapon but it lets the unit to move right after shooting - the value of that one a unit that normally sits and snipes is not to be underestimated.
*'''Incursor Squad:''' SEAL Team 6 marines. Downgraded from '''Infiltrators''' to '''Scouts 6"''' but fills a more coherent niche with '''Assault''' and '''Ignores Cover''' on their bolters along with Multi-spectrum Array buffing the rest of army. Their job is run up the board and use live bolt rounds to mark which victim gives +1 to hit. Essentially now instead of trying to compete directly with Infiltrators for infiltrating (was never going to work) they now function as the Astartes answer to Pathfinders. Marking targets for annilation, plus this coupled with OoM rerolls means you can nigh-guarantee kills. If the enemy gets too close, they can throw MWs (especially if its a vehicle), and have ''Sustained Hits 1'' knives (though not as good as Astartes chainswords).
*'''Infiltrator Squad:''' '''Infiltrators''' marines with ''Heavy'' bolt carbines that come with many other tricks like the {{W40kKeyword|Smoke}} keyword, 12" reinforcement denial, a 6+++, and CP Refund on a 5+.  Only OC 1, but still very good at grabbing an objective Turn 0 and then being very annoying to remove.
*'''Reiver Squad:''' Junior Night Lords, making enemies engaged with them suffer Battle-shock test at start of the Fight phase along with -1 aura to Battle-shock and Leadership tests. Got upgrades to give pseudo-jump packs so they can deep strike but robbing them of the ability to join a Reiver Lieutenant and grapnels so they can ignore vertical distance when moving. Their job is too support combats to force battleshock on enemy units thus weakening them up so your heavier-hitters will have an easier time in combat. They also got the role of picking off weak support heroes as they are the highlights of 10th, with their guns and Combat knife got ''Precision''.

====Gravis====
*'''Aggressor Squad:''' Giant drop-striking bundles of armor. Benefit greatly from the toughness 6 Gravis armour now gives and will need it given their weapon loadouts. Start with a '''Twin-Linked''' Ad6+1 flamer or can swap out for longer-ranged but significantly weaker boltstorm gauntlets and grenade launchers, but you should always take the flamers, as they improve their AP by 1 when shooting the closest possible target.  That said, outside of ''very'' specific situations, Infernus Squads or Heavy Flamer Devastator Squads should generally serve you better.
*'''Eradicator Squad:''' Gravis Marines toting melta rifles, each one a single-shot multi-melta at BS3+ base, while buying a multi-melta gives an extra shot at, functionally, -1 to hit on both shots. Total Obliteration lets you re-roll all hit, wound, and damage rolls when shooting their preferred prey of {{W40kKeyword|Monsters}} and {{W40kKeyword|Vehicles}}. Stack with an Apothecary Biologis and you will see things straight-up die when your melta shots crit.
*'''Inceptor Squad:''' The chunky fly boys are back. Have deep-strike in built and when they do they can come in as close to 3" from enemies but can't charge. Weapon wise they have seen a reduction of shots but still some good upgrades. One all their weapons are pistols so useable in combat. Their assault bolters have Assault, Twin-Linked and Sustained-Hits 2, so they can do some real work in high volume. In addition their Plasma Exterminators kept their old damage profile and now also have Assault and Twin-Linked. Meaning these guys with their move 10" can get around quickly while opening up on the enemy and being pretty hard to shift

====Terminator====
*'''Terminator Squad:''' Got the Terminator buff of T5 and a 4++. Fortunately, their WS and BS remain fixed at 3+ (unless you attack your Oath of Moment target, in which case you jump to 2+), which surprisingly actually stays where it is on the power fists (which remains S8 D2 but loses a bit with AP-2 and one less attack than the power weapons), but are stuck on WS4+ on the Chainfists (which are just power fists but with ''Anti-Vehicle 3+''). The power weapons, however, took a step down by just being power swords (no more axes, no more power mauls, just A4 S5 AP-2 D1 for everything). Storm Bolters are slightly nerfed due to no longer having Bolter Discipline constantly apply on these dudes, while the Heavy Flamer got a slight buff (it ignores cover now) and so did the Cyclone Missile Launcher (which actually got S9 on its krak missiles). The Assault Cannon took a nerf by losing its AP, but '''Devastating Wounds''' makes critical wounds more effective at penetrating saves and has excellent synergy with '''Oath of Moment''' against high-value targets, because you can re-roll successful non-critical wounds.
**Fury of the First makes them a lot more reliable now that its been made into a rule instead of a Stratagem. Being able to ignore any penalties to hit helps throw off a lot, but this also lets you add +1 to hit against anyone you target with Oath of Moment.
**The Teleport Homer remains as a means for reliable deep-striking, but now you need to set them up around 3" of the new pack-in beacon. This also requires you to use the Rapid Ingress Stratagem in order to use it, though you're not wasting a CP for it.
*'''Assault Terminator Squad:''' Any unit they charge must take a battle-shock test, which is a pretty solid gift to trap enemies. While they don't get the fixed WS like the standard termies, the Teleport Homers let them arrive wherever they need to be. While the lightning claws give them all the swipes you'd need to chop apart lighter foes, the thunder hammers give you the brute force to wreck MEQ and up and come with a bonus wound thanks to their shield - While there are weapons able to cut through W3 terminators, there certainly aren't many that can go through W4.
*'''Relic Terminator Squad:''' The old Tartaros and Caraphractii models, sadly mothballed into one statline with none of the benefits. While you get Fury of the First, you can't get a Teleport Homer to jump in on demand. Unique to their loadout is the Reaper Autocannon, the Assault Cannon's smaller, nicer younger brother. The sergeant also has access to a Volkite Charger or Plasma Blaster, two exotic weapons not found anywhere else in the army.  Unfortunately, this unit hasn't got any weapon choices genuinely ''better'' than making do with the other two squad types.
**They're fortunately a lot more viable as a flex unit as any model can pick up chainfists or twin claws, though they will lack the heavy punch of assault termies with hammers and shields. You can also buy a grenade harness so they can pull off the Grenades stratagem.

====Centurion====
Power armor for your power armor. Even Tougher and slower than Gravis armor at T7 W4 with inbuilt [TWIN-LINKED] triple bolters. At M4", they need a large transport to get anywhere fast, but they are so big they can only hold a min squad efficiently. 
*'''Centurion Assault Squad:''' Older Brothers of Aggrasors. punch Monster, Vehicle, and  Fortification with [SUSTAINED HITS 2] upscaled twin powerfists. A Guy could replace Centurion bolters to use Grenades Statagem, but that predicated you have CP to burn.
*'''Centurion Devastator Squad:''' what if Devastator Squad traded fire power for toughness and was better at landing those fewer shots? Decimator Protocols make them acreate against enemies on objectives. Replacing bolters with missile launchers is probably the best value.