Last Updated: 31-May-2016

Looking for a new mech? Why not the Crab? (shut up – lobster, crab, same diff)



The Crab comes in as yet another laser boat for the Inner Sphere. Laser-oriented mechs are certainly some of the strongest around for both IS and Clans, but all 4 of the Crab variants are almost absurdly similar, with quirks serving as the main differentiation. Three of the variants have identical weapon hardpoints and locations, and the fourth just has an extra hardpoint of the same type. It’s ridiculous.

The CRB-27SL and CRB-27B are both very solid mechs. The CRB-27SL has slightly worse hardpoint locations but it does have jumpjets, and the CRB-27B has asym build potentials, but I do generally lean towards the CRB-27B these days. The CRB-27 is the next best variant, much more cut-and-dry than the difference between the top two variants. Last up is the CRB-20 which has very little going for it.


Chassis-Wide Information


  • The profile is pretty unique, and that damage gets spread decently well on its own. Plus the front profile is pretty thin. It’s also a supremely small mech, but that may change soon.
  • The quirks are pretty appropriate; they’re small but only the CRB-20 has bad ones.



  • They all run pretty much the same builds…it can get a bit boring.
  • While the front profile is thin, the side profile is massive, making arms pretty useless for shielding – if the enemy can aim they’ll be able to hit your side torso.
  • There’s nothing spectacular about the mech – it doesn’t have great quirks, hardpoints, tonnage, or anything else really.


Generic Tips

  • You can’t really shield with your arms, but if a side torso is getting beaten up it doesn’t take much twisting to shield it by exposing more of your opposite side torso. And as a preventative measure, try to be always wiggling (unless you’re shooting of course) so that any damage gets automatically spread out a bit.
  • As long as your team isn’t all cowering, you’re usually relatively safe to poke. People don’t really focus Crabs. But yeah…if they are hiding be careful, you’re a bit fragile.



If you’re not familiar with my Inner Sphere Master Guides, each pretty much follows the same formula. Each variant gets its own section; within that section I try to include at least two main builds, each with a few variations on the core principle (if applicable).

Each build has one paragraph about the build itself – going over anything I feel is relevant to understanding it such as quirks, tonnage issues, how it fits the meta, my general feeling about it…just whatever. And then there’s a paragraph about using the build, going over tactics, tips, and whatever I feel is relevant to that, including links to L2P guides, on occasion.

I may miss a build that you like, or my builds may differ slightly from what you find works best for you because our philosophies may differ – I strongly encourage that you experiment for yourself to see what works best for you.

The modules are listed in order of which one is most important and the consumables I’ve listed are the ones that are generally the best, but while leveling the mech you may want to swap the less important consumable out for a UAV. That is, if you can afford to use consumables at all (they aren’t necessary, just nice, and if you’re low on C-Bills they’re not necessarily worth it).

On with it!



This variant has a 10+5% ERLL heat gen quirk (with a 10% generic portion), which is pretty good since heat gen is the most useful quirk for energy mechs. In addition, it gets 50% extra structure, 10% turn rate, and 20% torso yaw speed.

Build 1:

This is the most meta-friendly configuration for the Crab, boating 3 large pulses as many mechs do. The total alpha is a bit lower than I’d like, and the lack of a range quirk holds it back, but the ability to get high-DPS and decent trades helps it do great work.

Focus on corner-peeking in this build, and do it as often as your heat will allow. Your alpha isn’t huge, but it’s enough for a 50-tonner and you can keep it up for a while. You’ll have to get a bit closer than most other builds, so make sure to not get too far from your team and try to stick to the right flank of your team if possible. For more on Laser Vomit, check out the guide.

Mech Modules: Radar Deprivation, Seismic Sensor

Weapon Modules: LPL Range, LPL Cooldown

Consumables: Cool Shot, Air Strike

This sacrifices some of the range and duration that make the mech good, but gets 9 extra damage out of it. Not quite worth it in my opinion, but worth giving a go at least.

Weapon Modules: Medium Laser Range, Large Pulse Range

It’s a very different style, but still worth noting. Since this variant has the most hardpoints, it’s best suited to a Med Pulse build. You play a lot like a skirmishy brawler, avoiding a hard engage but not afraid to get in there.

Weapon Modules: Med Pulse Range, Med Pulse Cooldown


Build 2:

This takes advantage of the ER Large Laser heat gen quirk in order to take a pretty standard laser vomit build to the next range bracket without losing a whole lot. Running this build with normal Large Lasers instead of the ER’s does lose you a bit of range, but makes up for it with slightly less heat per alpha strike and a bit lower duration.

You can contribute to the fight at pretty much any range with this build. You’ll want to focus on the corner-peaking for most of the game, but if the range closes you may want to expose a bit more in order to add your mediums to the fight. For more on Laser Vomit, check out the guide.

Mech Modules: Radar Deprivation, Seismic Sensor

Weapon Modules: ERLL Range, ML Range

Consumables: Cool Shot, Air Strike



This variant has a 10% Pulse Laser-specific Range quirk with no generic portion. It also gets 25% extra structure across the board, the least of the variants, but 50% on the legs. There’s also a 5% turn rate and 20% torso twist speed quirk.

With range quirks and modules, your LPLs end up with an optimal of nearly 450m, which is pretty spectacular for weapons with their low duration and high damage. Everything else about the mech is pretty mediocre due to the low and spread mounts, but it works out to a decent package.

You’ll want to stick to the edge of your optimal range in this build, as getting much closer opens you up to getting jumped by brawlers and light mechs. In general, you’re best off poking on the flanks and/or in tandem with a few larger, more threatening teammates. For more on this sort of build, check out the Laser Vomit Guide.

Mech Modules: Radar Deprivation, Seismic Sensor

Weapon Modules: LPL Range, LPL Cooldown

Consumables: Cool Shot, Air Strike

Basically, you lose a heat sink and some speed for some extra damage and insurance in case you lose your arms. Plus, it’s a nice high mount.

Weapon Modules: MPL Range, LPL Range

This build sacrifices some of the range and heat efficiency for extra damage. Not a huge fan of the trade-off, but it can work.

Weapon Modules: MPL Range, LPL Range

Same idea, but it trades off a bit more range (on average) and a bit of damage for some sweet heat sinks, a jumpjet, and a fair bit of speed.

Weapon Modules: MPL Range, LPL Range



This variant has a 10% energy range quirk, 5% turn rate and 20% torso twist speed, and the big 50% structure quirks.

This is a solid build which takes the shorter side of mid-range for a decent alpha strike and DPS. This does limit you out of most of the main pre-engagement crap, but as long as you’re within your range you can contribute a good deal. Definitely nothing new, though.

This build is fully symmetric, but it is marginally capable of corner-peeking with its centerline weapons coupled with the arm. But most of the time, you’ll want to be fully exposed when you poke to get the most out of your build. Since it is a shorter-range build, you want to stick with your team’s protection and stay in cover if you can’t find a way to get in damaging range (I’d say you don’t want to poke outside of 500m at all if you can help it). Your big two tactics for this build should be rotating and flanking in general. For more on Laser Vomit, check out the guide.

Mech Modules: Radar Deprivation, Seismic Sensor

Weapon Modules: Medium Laser Range, LPL Range

Consumables: Cool Shot, Artillery Strike



This variant comes with a 7.5+7.5% Large Laser Cooldown quirk offensively in addition to the regular defensive and mobility quirks. The cooldown quirk isn’t terribly helpful as you’re mostly heat-limited, but it can add a bit to your DPS until you overheat. And you do also have a higher engine cap – not useful most of the time but sometimes…

Build 1:

Again, this works with the quirks to make a nimble short-to-mid range skirmish-style mech. While the other laser vomit-style builds for the other Crab variants focus on high alpha damage at a uniform range bracket, this has more differentiated weapons and a lower alpha. The difference isn’t exactly favorable to the CRB-20, but it does have the benefit of much lower cooldowns, allowing for more consistent poking right up to the point where it overheats.

This build is oriented around laying down DPS through consistent pokes or exposure rather than getting a high-alpha longer-range burn on the target. Play to that by keeping up the aggression on the wings of the enemy team – you won’t usually have the higher alpha damage, but you’ll usually have better sustained damage (right up to the point where you overheat). Just don’t die, and if you’re running hot, keep to cover while you cool down. If you can’t stay in cover while running hot for whatever reason, stick to the Large Lasers as they are more heat-efficient. For more on this style of build, check out the Laser Vomit Guide.

Mech Modules: Radar Deprivation, Seismic Sensor

Weapon Modules: Medium Laser Range, Large Laser Range

Consumables: Cool Shot, Artillery Strike


Build 2:

The idea behind this is to take advantage of both the energy cooldown quirk and the higher engine. This ends up giving you a pretty decent brawler, with good speed, plenty of heatsinks, and pretty nice DPS. The downside is that you can’t do any ranged stuff at all with the build, and your low alpha makes trading a losing proposition. And seriously, it’s a Firestarter build, not a medium mech. Blech.

This is a pretty typical brawler for the most part, focusing on staying healthy until it can get in range to do damage. Stick with your team or with a wolf-pack (you can even keep up with friendly lights most of the time as long as they’re not doing anything to risky) and try to get in shots when you can without exposing yourself to the whole enemy team. Use flanking maneuvers or rotations as an excuse to get closer and pick off stragglers if possible.

Mech Modules: Radar Deprivation, Seismic Sensor

Weapon Modules: MPL Range, MPL Cooldown

Consumables: Cool Shot, Artillery Strike

It’s a fair bit slower and a little bit hotter, but it’s also a bit more survivable. Losing an arm, or even both arms, or even both side torsos won’t even get rid of most of your firepower so it does make some sense to run this with a STD engine, but personally I’m not a huge fan.


Pilot Skills

I’ve figured that this is the best skill order for pretty much any mech, and so I’m just going to customize it for mechs that have to emphasize unusual pilot skills.

Basics: Cool Run – Heat Containment – Hard Brake – Kinetic Burst – Twist Speed – Twist X – Anchor Turn – Arm Reflex

Elites: Speed Tweak – Fast Fire – Quick Ignition – Pinpoint

Then just master it. The only one that I think is currently pointless is the CRB-20 as the others have decent-ish quirks. That may change come rebalance time, so check the current quirks and see which ones are for you if this guide is out of date.


And that’s that. I hope you enjoy your mech, let me know if you have any questions, and as always glhf

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