Engineer
Explosive Chemical Build
This is a very strong build in both solo and group games, its capable of both holding its own and complimenting pretty much any teammate loadout. The LOK-1 Rifle is pretty much a shoot and forget type weapon, with very little actual aiming required. Bullets will auto travel to their target and practically never miss. The build revolves around a 3 Lock system explained on the weapon itself. Effectively, this makes the LOK-1 a very strong mid-long range weapon to deal with anything between grunts and Praetorians. There are 2 downsides to the LOK, effectively dealing with hordes, and tough enemies. While it can do both, it requires a lot of ammo to take our tough enemies, and our small lock-on angle makes targeting large hordes hard to do. There are 2 secondary weapons to compliment this downside. Breach Cutter with Return to Sender is very strong against single targets, able to deal “double” damage when the beam returns, and it’s ability to travel through enemies deal with hordes instantly. Alternatively, if you want a bit more range, Fat Boys in the Deepcore melt hordes instantly, and deals good damage vs Praetorians, but due to it’s very small ammo supply, it’s not a reliable choice if you need to use it for both hordes and Praetorians/Oppressors. The choice is up to preference, as they are both very strong.
Weapons
LOK-1 Smart Rifle
T1B – 
Expanded Ammo Bags (+72 Max Ammo)
T2A – 
Macro Lens (x2 Lock-on Range, -80% Lock-on Angle)
T3A – 
Electro-Chemical Rounds (+20% Damage to Electrified and Burning enemies)
T4A – 
Shutter Speed Sensor (-15% Lock-on time)
T5A – 
Electric Generator Mod (Targets with 3 or more locks are electrocuted by the first bullet. 12 Damage per second. +80% Slow for 3 seconds)
Explosive Chemical Rounds (Targets with 3 or more locks, the last bullet that hits causes an explosion. Explosion does 50 damage, and causes fear on nearby enemies. -5 Damage, -36 Max Ammo)
Great choice if you want your gun to aim for you. The playstyle with this weapon is to get 3 Locks on a target, or per target, and fire. No more, no less. The build is centered around 3 Locks and shooting. T3A increases damage against electrocuted or burning enemies. T5A electrified enemies on the first bullet, so the following 2 bullets deal extra damage. Our overclock also revolves around our 3 Lock build. When the third bullet hits (last bullet) on an enemy with 3 Locks, an explosion will occur on the enemy that damages enemies around them and applies Fear to them. Rinse and repeat this 3 lock setup to maximize damage and help with overall ammo economy.
Breach Cutter
T1A – 
Prolonged Power Generation (+1.5 Projectile Lifetime)
T2A – 
Expanded Ammo Bags (+6 Max Ammo)
T3A – 
Quick Deploy (-0.2 Plasma Expansion Delay)
T4B – 
Disruptive Frequency Tuning (+100% to Stun for 3 seconds)
T5B – 
Plasma Trail (Leave behind a plasma trail, deals damage for 4.6 seconds)
Return to Sender (Holding down the trigger activates a remote connection, release to cause the line to move back to the gun. -6 Max Ammo)
With the LOK dealing effectively with most enemies, the Breach is used when you get overwhelmed by enemies or need to deal with Praetorians/Oppressors. The Breach Cutter is an effective tool to pair with our long range rifle. Perk and overclock selection help maximize the effectiveness of this weapon, without sacrificing some of the features needed to work with the LOK.
Alternate
Deepcore 40mm PGL
T1B – 
Extra Ammo (+2 Max Ammo)
T2A – 
Expanded Ammo Bags (+2 Max Ammo)
T3C – 
High Velocity Grenades (+180% Velocity)
T4B – 
Nails + Tape (+1m AoE Radius)
T5B – 
Spiky Grenade (+60 Direct Damage)
Fat Boy (x4 Area Damage, +1 AoE Radius, -70% Max Ammo, -30% Velocity, Leave behind 8m Radioactive zone for 15 seconds)
An alternative to Breach Cutter is the Deepcore, essentially a mini nuke with Fat Boy overclock. One round from this grenade launcher can devastate hordes before they even have a chance to do anything noticeable. Be careful to not hurt your allies as this will leave a massive radioactive area around the impact zone. Not the best for single target damage, while it will still hurt any Praetorian/Oppressor, we don’t take full benefit from the Fat Boys overclock, and our ammo capacity is severely small. You could use Hyper Propellant instead, but then neither of the weapons in this build can really effectively deal with hordes.
Equipment
LMG Gun Platform
T1A – 
Gemini System (+1 Max Turret, +90 Carried Ammo)
T2B – 
Quick Deploy (-2 seconds to Construct)
T3B – 
Stun (+20% to Stun)
T4A – 
Defender System (+5 Damage, Increase )
Gemini System (T1A) allows more coverage, on more angles and does more total damage when combined. While the MKII turret offers more damage, if both Gemini turrets are shooting the same target, they do more damage overall. Being able to damage 2 separate targets or to cover 2 different angles is more valuable then 1 enhanced turret.
Platform Gun
T1B – 
Expanded Ammo Bags (+8 Max Ammo)
T2A – 
Plastcrete MKII (Reduce Fall Damage)
T3B – 
Repellant Additive (Bugs avoid walking on platforms)
Main points here are the increase in ammo, and bugs avoiding the platforms (when possible). T2 only has one option so there is no choice to be done. Option to take more ammo instead of the bug repellant (T3B) since the bugs will walk on the platforms if they need to regardless of the repellant.
Owl Amor Rig
T1A – 
Improved Generator (-1 Second Shield Recharge Delay)
T2B – 
Healthy (+20 Max Health)
T3A – 
Hazmat System (+50% Poison Resistance)
T4C – 
Breathing Room (+3 Second Revive Invulnerability)
Armor is pretty flexible in perk choice, I enjoyed the following perk combination. It will always be more beneficial to take T2B (Healthy) for the increase in health, rather then shield, which only gives +5. Shield also regenerates, while health does not unless you gather red sugar or a re-supply pod. I also found T4C to be helpful especially on harder difficulties were you might be revived in the middle of a horde of enemies, the extra seconds in invulnerability will really help to get to a safe distance to re-group.
Lure
OR
Shredder Swarm
The Lure grenade offers great versatility with engineer builds. It’s main quality is distracting enemies, while it does have a small explosion at the end, it does not do a lot of damage. The Lure is really helpful on higher difficulties to help with repositioning, getting a revive, or to just cluster enemies together for an explosion.
The new Shredder Swarm grenade is also really strong but is more a damaging grenade, rather then a utility grenade. The grenade will spawn a group of shredders that rip through bugs with very decent damage. They won’t do very much against a Praetorian, but will definitely help out in a horde.
Passive Perks
Thorns
Resupplier
Elemental Insulation
Deep Pockets
Thorns : One of the better perks for the Engineer, since we don’t have any great crowd control against swarmers and alike (unless your turrets are up or you want to spend precious secondary weapon ammo, this perk really helps up out. It is capable of killing small enemies instantly after they hit us. It helps the overall crowd control capabilities. Definitely worth grabbing.
Resupplier : Another great perk that I recommend across all classes. If resupplying 50% faster wasn’t good enough to have in a pinch, gaining 25% more health each time is just the cherry on top. One of the best passive perks to have in my opinion.
Elemental Insulation : An optional choice, but a relatively strong one depending on the cave biome you’re in. Take 30% less damage from all elemental sources. This includes; Fire/Frost/Electricity/Poison/Radiation/Heat and Cold.
Deep Pockets : Another optional choice, this is more a quality of life perk choice, it allows you to hold +15 more minerals of each type. This can be particularly helpful when gathering resources from hard to reach places, and in general limit the amount of trips needed to deposit them. This especially shines in any mission that does not have a Molly.
Active Perks
Iron Will
Field Medic
Dash
Beast Master
Iron Will : Once per mission, you can revive yourself for 12 seconds before going back down. This may not sound like a great perk at first, but it can be a game saver. While on it’s own, not very strong, you can revive allies who can then revive you in turn. Alternatively, even in a solo game, there is a way you can stay alive, effectively turning this into a permanent self revive option. If you gather health within the 12 seconds, you will stay alive. This can be from Red Sugar, Resupply pods, or other means (Vampire Passive Perk). This perk is pretty strong on any class to keep for emergency situations. Recommended saving it’s use until absolutely necessary.
Field Medic: 100% a group game perk, do not use if playing solo. This perk should definitely be equipped when playing in a group game. The ability to revive allies 30%, fear enemies after reviving an ally, on top of the activation option of instantly reviving an ally, this perk can save games on its own.
Dash : Gain a very short burst of speed that can be used every 25 seconds (at max rank). This burst of speed ignores any slow effects you may be suffering, which can be really helpful when stuck in goo or any other slowing effects. You can even Dash while holding heavy objects like Aquarqs. This is particularly strong on slower classes, like the Engineer, in order to keep up with the team, or to escape a tight situation quickly.
Beast Master : A generally fun, and useful support perk, I found it’s best use in solo games, but it is not restricted to this mode. This perk allows you to convert a “Grunt” level enemy to be a companion. This includes “Grunts”;”Slashers” and “Guards”. I found Guards to be the best ones to grab, from the available options. It has the most health, which means, will survive the longest while grabbing enemy attention. In a pinch, the Slasher is also very helpful as it has the most damage to kill enemies from the available options. In the end, this is up to personal choice. There is a 5 minute cooldown between uses, allowing you to repeatability use this perk.
