“I am become death, the destroyer of worlds”- J. Robert OppenheimerDo you ever wish you could just turn off your brain while playing on the hardest difficulty? Do you like big damage numbers? Are you tired of enemies surviving more than a single shot from your build? If you answered yes to any of these questions, then the Fusion Cannon is the perfect weapon for you. This build guide aims to show you how to make the most of this fearsome weapon, allowing you to obliterate anything in your path on even the highest difficulty.
https://underrail.info/build/?HgsFBQMIBQk8wqAAAFoAAFBJXgAAX18KX1AAAAB9AAA8KDErO8Odf8Oew59KwprDolpNKcKHwrRLd-K0lAXivrwF4r-GBd-8What is the Fusion Cannon?The Fusion Cannon is a unique heavy weapon found in the new DLC area, the compound. It’s relatively easy to acquire if you know what you’re doing, you just need 100 lockpicking to open the vent at the entrance area, enough stealth to sneak past patrols (~130 should be enough), and enough perception to sneak past the laser tripwires protecting the cannon (8 should be enough).
It’s important to know that there are some unique quirks of the weapon that aren’t covered in the description. The cannon works like the Naga energy attack, dealing damage to everything caught in the blast in the same radius as an HE grenade. Enemies directly hit by the cannon take full damage, while enemies at the edge of the blast radius only take 50% damage. Additionally, if you take the Disassemble feat, you can break down the Fusion Cannon into its components and reassemble it, allowing you to replace the fusion emitter and plasma core. This improves the damage and max energy, and additionally allows you to gain the benefits of the Practical Physicist and Power Management feats. The default version of the Fusion Cannon has an ~q115 fusion emitter, but a crafted emitter can realistically go as high as q160. A q159 emitter will net you 272-350 damage, so it's well worth it to disassemble the cannon and replace the fusion emitter.
What’s the damage?With 11 effective per at max level you’re looking at 758-976 damage, with 125% crit damage from practical physicist. That’s pretty good, but the Fusion Cannon gets a lot better when you look at the feats that it benefits from. Being a heavy weapon, the Fusion Cannon benefits from Heavy Metal, which provides an 130% damage increase with full damage spec and Iron Head/95% Armor/Reinforced Tungsten Boots. On top of that, it also benefits from High Technicalities, which with spec at 13 int provides an additional 80% damage boost. Tricky Trajectory also applies, for a 10% damage boost and 30% evasion ignore. The cherry on top is Bullet Trance, which provides an extra 50% damage when specced once you reach max stacks. With a crit, max damage roll, and all the relevant drugs the highest damage you could get with this build would be 14,675 damage (350 base * 3.72 skill damage modifier *1.5 Crit * 2.3 Heavy Metal *1.8 High Technicalities *1.1 Tricky Trajectory * 1.5 Bullet Trance * 1.1 Serial Killer/Beast Tattoo). Except that number is incorrect. On a test run of this build (15 int version, no serial killer, no bullet trance, q152 cannon) I was able to achieve a damage roll of 25936. I believe that the Fusion Cannon has a hidden damage modifier on attacks, although some theorize that the High Technicalities scaling on the weapon may be broken. Regardless, now that Bullet Trance works with the Fusion Cannon, you should be able to deal upwards of 30k damage crits with high quality parts.
GearGear for this build is somewhat complex, you’ll need to use specific gear to mitigate the fragility of having 3 con/ make the most of Heavy Metal.
Weapons- Sledgehammer- Only used in the early and midgame before we get the Fusion Cannon, helps mitigate the high ammo costs of using heavy weapons and provides a quieter alternative than a machine gun burst.
- Refurbished N60 The Warthog- We want a 35 ap LMG for when we have fatigue/temporal dilation, and the Warthog is our best option. It has cheap and common ammo, which makes it preferable to crafted LMGs, and will mainly be used when we get cornered/surrounded and can’t safely fire the Fusion Cannon.
- Fusion Cannon- We can get this as early as level 15, once we reach 100 effective lockpicking with the Jackknife and Eel sandwich. The main weakness of the weapon (apart from the crippling vulnerability to EMP grenades) is the close quarters penalty, if the weapon misfires and you get caught in the blast you’re dead. With Strafe and Contraction you can escape melee range and cook your pursuers, so ensure that you don’t get cornered or surrounded. We take 135 ™ to reduce the chance of a backfire, so on the first turn of combat cast Contraction and try to save 10 ap. On the second turn of combat you can pop adrenaline to reach 100 ap, allowing you to fire two Fusion Cannon blasts in a single turn. Also, carry lots of electronic repair kits, durability loss is based on damage, and since you do such massive overkill you usually need 1-2 repair kits after every fight.
Crafting high quality fusion emitters is a real pain in the ass, since quality is determined by the lowest quality component from the five component parts; laser emitter, electroshock generator, circular wave emitter, electromagnetic field stabilizer, and high efficiency energy converter. I recommend hoarding ~q120 parts so you can reassemble the cannon to benefit from power management and practical physicist, and then hoarding ~q150 parts to make an endgame cannon. If you aren’t using merchant refresh, you can’t realistically craft an emitter above ~q152. Don’t bother waiting until the Deep Caverns to craft your cannon, you’ll probably only find 1-2 relevant high quality parts.
ArmorHelmets
- Iron Head- This is the highest armor penalty helmet available, although it’s shit defensively. Not worth it at later levels once you’ve crafted a good helmet unless you really want the highest damage possible.
- Solid Padded Super Steel Helmet- Your best option for headgear, gives flashbang immunity while providing some crit reduction and extra resistances. The penalty loss from Iron Head doesn’t matter, you’ll still deal more than enough damage with Heavy Metal if you wear Metal Armor.
Armor Suit
- Sturdy Super Steel Armor w/ Tichrome Reinforcement- Sturdy vest is by far the best vest here, a high quality vest is an ~75% hp boost at high levels and an even bigger boost at lower levels. To put things in perspective, at level 30 on Dominating a 3 con psi character with a q160 sturdy vest has 376 hp, the same as an 8 con psi character without the vest. You should always use Super Steel as the base material due to the vastly superior mechanical resistance, but that benefit doesn’t matter once you reach the 95% mechanical resistance cap from your helmet/armor/boots. Q170 super steel has the same energy resistance as q150 TiChrome but much worse heat resistance, so once you reach the mechanical resistance cap you should use a combination of TiChrome/ Super Steel Plates to maximize your resistances to heat and energy damage. Tichrome also provides 1% more armor penalty over Super Steel when reinforcing, so if you want a 95% penalty suit you’ll need 3 TiChrome plates for reinforcement. High quality TiChrome is a real pain in the ass to get, since your only options are the Waterway facility and Deep Caverns, so just use the q150 plates Leonie sells sometimes.
- Biohazard Quad Plate Tungsten Armor- This is the best option for some parts of Expedition. It’s high enough mechanical DT to block all damage from leper serpents, and the Bio DT from a good vest makes you immune to Locusts and very resistant to heartbreaker spit when combined with a gas mask and biohazard boots.
Boots
- Reinforced Tungsten Boots w/ Solid Padding- Normally your best option for maximizing penalty on boots, only worth it if you really need the extra damage.
- Undersized Buckle Shoes- Only available from the Saint Patrick’s Day seasonal event, they’ve got 22% more penalty than reinforced Tungsten at the cost of having basically no defensive benefit. Not worth it unless you want the highest damage possible from Heavy Metal.
- Reinforced TiChrome Boots- With high quality plates you can reach 95% mechanical resistance with a combo of super steel and TiChrome gear. Boots provide about twice the resistances as Helmets of the same material, so it’s better to use Ti boots over SS boots. In my playthrough I reached 95% Mechanical DR, 68% Heat DR, and 99% Energy DR with the SS Helmet/ SS/Ti Reinforced Armor/ Ti Boots, although I never got lucky with finding any q150+ Tichrome.
GameplayYou shoot enemies, they die, they shoot you, you don’t die. Simple as. You play as a featless hammer build in the early game, an LMG build post depot A but before you reach level 15, and then become a walking WMD once you get the Fusion Cannon. The Fusion Cannon produces noise at the center of the explosion, so what will frequently happen is everyone caught in the explosion dies, combat ends due to a lack of enemies, and then everyone else in the zone congregates where the explosion landed, setting you up for another obliteration. At level 25+ nothing can withstand your blasts, but before then there’s a few enemies on Dominating who can give you trouble:
- Sea Wyrms- While submerged they have 50% resistance to all damage and +300 evasion, which makes them evade 67.5% of area damage when accounting for tricky trajectory, giving them an effective hp of ~3785.
- Naga Protector- Boasting an impressive 1.5k hp, 50% electric resistance, and 80% energy resistance, these are the toughest basic enemies to deal with, having an effective hp of ~4286. In the quad Naga fight in particular they can survive blasts if they get clipped by the edge of the explosion.
- Final Boss- The final boss has 8k hp and 65% resistances, giving him an effective hp of ~17,778. Pretty impressive, but fairly easy to oneshot since you can build up Bullet Trance stacks by killing minions.
- Carnifex/Magnar- While under adrenaline Carnifex meets the evasion cap even with Tricky Trajectory, and thanks to his 20% electric resistance his effective hp is ~20534. Magnar is a similar story, although he’s slightly weaker due to his lack of electric resistance. Magnar’s ghost is also quite tanky, he’s got ~60% resistance to the damage on top of high evasion but has significantly less hp than his base form.
- Master Skull Smasher- Probably the only enemy that you’ll have trouble oneshotting. His blast suit and resistances grant him ~90% damage reduction against the Fusion Cannon, and on top of that he’s got ~5% evasion, turning his already impressive base hp of 2360 into an effective hp of ~25813.
ConclusionThe Fusion Cannon is an absolutely insane weapon and has some of the highest damage possible in the game. While a plasma pistol crit execute with the proper special attack damage boosts could potentially deal more single target damage, the Fusion Cannon certainly blows all other weapons out of the water with its overwhelming damage and ease of use. Any build with investment in heavy guns should consider using the Fusion Cannon, as just the base weapon with the Heavy Metal feat is enough to one shot all but the toughest enemies. Despite its drawbacks, I firmly believe that the Fusion Cannon is the best weapon in the game.
Merry Christmas!
