The Fafnir is best described as a turret assault mech - slow and clunky, but heavily armed and armored. In many ways it's similar to the Annihilator with its extremely heavy-hitting loadouts.

Fafnir has relatively high weapon mounts, a high engine cap, good quirks, and some ECM options, some of the best possible attributes on paper. The downside is that the CT is very large. Don't be fooled by this mech's high armour, in reality it is fairly squishy and rolling damage away from the CT is very difficult.

The main thing that you should keep in mind when playing Fafnir - choose your peeks/trades wisely! This mech can't tank like the Annihilator and you will find yourself dead quite fast if you're not careful. But if you do play it smartly, then you'll find the end screen results very satisfactory.

Finally, if you're looking for your first 100tonner to buy, I'd strongly recommend to choose the Annihilator - it's that much more forgiving. Fafnir would be a good choice for more experienced players that can navigate maps well and know the dos and don'ts of slow assault mechs.

Variants LA LT CT RT RA HD JJs MASC MaxEng Accel Twist Pitch
FNR-512ECM211 0 FALSE 325 8.5 kph/s 100o @ 58.5o/s 20o
FNR-5B21ECM121 0 FALSE 325 8.5 kph/s 100o @ 58.5o/s 20o
FNR-6U2222 0 FALSE 325 8.5 kph/s 100o @ 58.5o/s 20o
FNR-5E2222 0 FALSE 325 8.5 kph/s 100o @ 58.5o/s 20o
FNR-6R11111111 0 FALSE 325 8.5 kph/s 100o @ 58.5o/s 20o
FNR-WRH1122ECM1111 0 FALSE 325 8.5 kph/s 100o @ 58.5o/s 20o
FNR-JH2222 0 TRUE 400 10.8 kph/s 100o @ 67.5o/s 20o


A ballistic-heavy variant with ECM. The ECM is a nice addition to help offset the drawbacks of high-facetime ballistic builds (especially crucial for squishy Fafnir). This variant has a few very good builds, but none of them are unique and can be run on other variants or chasses.

Dakka w/ ECM

Added by Lizzee / Last updated: 27 Jun 2019

A classic dakka build that's possible on many different mechs. With a 60-damage alpha, good DPS, and ECM, this mech is very well-suited for solo queue. Gameplay is no different from any other UAC boat - find yourself a good position and start dishing out as much dakka as you can. Duck back into cover only if you're heatcapped or if you find yourself doing less damage than what you take in return.


Added by Tarogato / Last updated: 12 Mar 2023

Similar builds are better on the FNR-5B, but this has CD quirk for the Gauss if you find that useful.

Quad LB10

Added by Lizzee / Last updated: 27 Jun 2019
4x LB10 + ECM (STD295)  

The Fafnir isn't necessarily a spectacular brawler, but this build has crazy DPS, runs ice cold and absolutely destroys mechs once their armor is gone. ECM really helps for getting into that 200-300m sweetspot where LBXs actually start doing work, so despite having worse hitboxes than an Annihilator and worse agility than the Cyclops, FNR-5 is still a very nice pick for a solo queue LB10 platform.

Quad RAC2

Added by Lizzee / Last updated: 27 Jun 2019
4x RAC2 + ECM (LE325)  

With this build you're supposed to ignore the ghost heat and just fire all four RACs. While at first glance it may seem like a bad idea, plenty of DHS and additional quirks handle the heat very well. Your main targets are slow heavies and assaults - this build feasts upon them. Avoid wasting DPS on fast movers unless they pose a big threat to your team. This loadout requires you to stare down targets and while ECM helps offset the issues that this brings, you should still choose your peeks very carefully.


Added by SirEpicPwner / Last updated: 2 Apr 2023

Quad LGauss

Added by denAirwalkerrr / Last updated: 15 Jun 2019
4x LGauss + ECM (LE300)  

No, you shouldn't run Stealth on this. This is already a build which has mediocre damage output, and being forced to 40kph or slower is just not worth Stealth. At the ranges where LGauss is optimal, ECM is plenty enough to keep you off of radar.


Dual ballistic with the most energy hardpoints makes this variant an ideal platform for gauss builds. The hard-hitting loadouts means that FNR-5B is not hindered by a lack of offensive quirks. It also has ECM, which makes it rather forgiving for the average player.

HGauss wubs

Added by Lizzee / Last updated: 27 Jun 2019

Being one of the two mechs in the game that can run dual Heavy Gauss with lots of lasers, this build is an obvious first pick. Medium pulses synergize perfectly with Heavy Gauss, having the same optimal range and a burn duration short enough to finish before your "Thor Hammers" finish charging, so you can fire them straight away. As a result we have a build with 80-pinpoint untwistable alpha - enough to core or outright one-shot many mechs before they can even react. ECM helps you get into that 250-300m sweetspot, where this build starts decimating enemies left and right.


Added by denAirwalkerrr / Last updated: 12 Mar 2023

This build has more range than the MPL version - you can shoot Heavy Gauss up until ~500m while still having respectable damage. The build's main drawback is that ERML have a longer burn duration than MPL, so they are less deadly and have less synergy with the HGauss charge mechanic - if you fire your lasers while charging, you'll have to wait longer for the lasers to finish before you can adjust for lead and loose the Gauss.

This build is just a bit more safe than the closer-ranged MPL one, so if you for some reason struggle with that one, you can definitely try this.


Added by Lizzee / Last updated: 21 Jun 2019

This is the ultimate IS gaussvomit mech. If you like gaussvomit gameplay but not the short range nature of HGauss or long burn duration of clan lasers, then this build is for you. ECM really makes this build shine since you can safely sit at 500-600m where most enemies won't even notice you and fire alpha after alpha at them. The build runs fairly cool and in general is very well-suited for QP.


Probably the weakest variant of the bunch. The FNR-6U has a non-optimal hardpoint layout, is lacking in quirks, and doesn't have ECM. Available builds however are not all that terrible.


Added by Lizzee / Last updated: 27 Jun 2019
4x UAC5 + 4x ML (LE325)  

Not a particularly outstanding build, but it's still pretty nice. Having the ballistics in your wide arms is a significant drawback due to convergence issues against moving targets. Still, you just can't go wrong with quad UAC5s on IS mechs. Medium lasers are there to add some punch to the build and help out whenever you suffer from too many jams - with decent output from the UAC5s, you have no excuse to overheat by firing the lasers when you can't afford to.


Added by Lizzee / Last updated: 4 Jul 2019
4x HPPC (STD320)  

Probably the most optimal mech for running quad HPPC. By comparison, the Awesome and Highlander run too hot, and the Annihilator is slower and has low mounted arms.

With a 20% velocity quirk and 60-pinpoint salvo, very few mechs will want to trade with you. While this mech has 20DHS and a heat quirk, it still runs pretty hot, so watch your heat bar. Be very careful against fast targets - this build has no backup weapons, so its weakness is anything that can rush into your ~90m deadzone.


A ballistic-missile only variant. Despite the lack of energy, this variant is rather versatile in terms of build types. The FNR-5E lacks ECM, but offers a 10% range quirk as compensation.


Added by Lizzee / Last updated: 27 Jun 2019
2x LB20 + 4x SRM6a (STD275)  

This is the only IS mech that can do the "Scorch" build and even being a 100-tonner it still barely fits it. It can't truly rival the Scorch itself or even the MCII-2, but it's still a very deadly mech with it's 92-point alpha. Its main disadvantage is the poor convergence with the SRMs and slow engine.

This build is not recommended for less experienced assault players due to being a brawler that moves very slowly, and will struggle without a team to back it up.


Added by Lizzee / Last updated: 27 Jun 2019
2x UAC10 + 2x UAC5 (STD300)  

This build is almost identical to what is listed for the FNR-5. This variant loses the ECM in favor of a range quirk, while adding back a heatsink and some ammo. While definitely not as forgiving in terms of positioning as its ECM counterpart, this version is slightly more deadly.


Added by Lizzee / Last updated: 27 Jun 2019
4x LRM20 + bAP (LE325)  

Started as a meme build, this is actually one of the most deadly LRM boats, in part thanks to the heat and velocity quirks.


This variant is usually overlooked in favor of FNR-5B that has ECM. Indeed, -6R lacks ECM and has almost the same hardpoint layout except having one less energy slot, but instead it offers a 10% cooldown quirk that makes it a very potent mech.

HGauss wubs

Added by Lizzee / Last updated: 27 Jun 2019
2x HGauss + 4x MPL (STD295)  

Very similar to FNR-5B, this mech loses ECM in favor of significantly higher DPS output provided by the global cooldown quirk backing the Heavy Gauss. If you feel confident about your positioning such that you don't need to crutch on ECM, you may want to try this build.


Added by Lizzee / Last updated: 27 Jun 2019
2x AC10 + 2x HPPC (STD300)  

The Fafnir is the only mech that run this build effectively (others tend to have poor mounts). This build offers you an insane 50-PPFLD alpha at up to 500m. It runs pretty hot, but if you find yourself heatcapped you can fire just the AC10s which by themselves are pretty heat neutral.

While other Fafnir variants can run this build, the FNR-6R is the best due to its cooldown quirk and all torso mounts for nice convergence.


A brawl-oriented hero with a very good mix of ballistic, energy and missile hardpoints with ECM on top of that. While not as tanky or agile as the Atlas, it packs a fair bit more punch, having more hardpoints with brings it near 100-damage alphas.

Brawl w/AC20

Added by Lizzee / Last updated: 27 Jun 2019

A very deadly build that can kill most mechs in one or two salvos. Against faster targets remember to fire your MLs separately from everything else to ensure that everything goes where you want it.

ECM really helps this mech to get into close range where it can start shining. The main weakness is the missile hardpoints being spread across the entire mech which hurts the SRM convergence compared to alternatives like the Atlas.

Brawl w/HGauss

Added by Lizzee / Last updated: 27 Jun 2019

Compared to the AC20 version, this build has more alpha and a bit more range, but it is slower, hotter and more fragile (HGauss can explode). It also may be harder to play for inexperienced players, due to the HGauss requiring charge and causing reticule shaking.

MRM120 w/ ECM

Added by Lizzee / Last updated: 27 Jun 2019
4x MRM30 + ECM (LE325)  

A pretty good MRM boat. While Annihilator or Cyclops are probably gonna do the MRM boating better, Wrath offers an ECM that helps offset it's chassis' innate flaws. Builds main drawback is(again) - convergence issues with arm mounted missile hardpoints.



AC2 dakka

Added by SirEpicPwner / Last updated: 3 Apr 2023
8x AC2 (LE300)  

Quick info:
InnerSphere assault
100-ton battlemech
Avg Engine 305 (49.4kph)

Solaris7 coming soon
Public Vote coming soon

FNR-5BHGauss wubs