*check the 2nd page for some addendums due to recent updates
This is my personal custom build, my favorite of all that I've played.
https://underrail.info/build/?HgUNDQMDAwYAQADCoMKgwqAAADEsAE1ZEVFUAAAAwqBwAAA5JCs_wowSThPCh8KNBkdLPMKIwqUqwrPDjm0abMKewp_CoMKhwp3CreKnlgXisaAD4rKIBeKyiQLfvwWin initiative, drug up, race up to enemy, stun/root/incap, expose weakness, flurry, move to next enemy or run away behind cover, stasis if necessary. Use blitz if you have the mp at the start of a fight, then you'll get your fancy footwork mp and can sprint. Later on you can premed your stasis to fit another flurry into your round. That's the essence of this build. When flurry inevitably misses, use LTI and switch to your knife (see "equipment" below). You'll be constantly juggling cool-downs and drug durations. I have yet to face a fight this build can't handle, though granted I've played many sword builds now and really know what I'm doing.
If you've never had such high evasion (especially with siphoner armor), you can throw the strongest grenades at your feet, unbuffed, with no shield, and barely take damage. The only traps you need to watch out for are EMPs. You might think with 3 con and psi aids you might be too squishy, but remember you can use aegis and morphine for 2 AP each, and infused siphoner armor does grant a fair bit of protection, and your shield helps block whatever does manage to hit you. You will get netted or blunder into bear traps, but you have escape artist and limited temporal increment, so you should be fine, especially if you used your mp to make enemies have to run over to you at the start of their turns. At the highest levels you can reach over 1000 dodge/evasion, especially with vitality powder, super-soldier drug, and all-in together. I typically don't use adrenaline until I need the AP so as to put-off the fatigue as late as possible; with future orientation/psycho-temporal acceleration/limited temporal increment, you can be under contraction permanently (until you run out of psi reserves anyway). I keep precognition active during battle, carefully eyeing my psi points and psi-booster cool-downs; psionic accelerators are worth using on this build later on. Flurries need to deal mechanical damage or they fail, so make sure to use Expose Weakness on tanky enemies first; later in the fight your onslaught/taste for blood/crit chance/emitter will carry you against tanky enemies.
Whether you want to max blitz spec or future orientation spec is up to you; blitz will pay off the increased AP cost from FO over the course of a long battle, but only if you get to use another blitz and you might miss those AP in a given round when blitz isn't available. Max out your flurry specs first regardless.
If you were willing to pay the psi penalty and can find the spare skillpoints, premeditated electrokinesis is a fantastic way to start a flurry, replacing recurrance in your slots. Also, I'm toying with the idea of dropping persuasion and premeditation and picking up quick tinkering and some traps/chem points instead (QT spec instead of blitz) so I can plop down a mkV HE mine or a mkIII plasma mine in combat for free and step on it when enemies are crowded around (like when exiting a stasis). That's pretty cheesy though, and I like having persuasion.
EQUIPMENTRoot soda should be your primary food to ensure that you basically always win initiative. It's cheap and available the entire game from level 1 at SGS. In the second half of the game you'll get twitch, which you can either stack with root soda or replace root soda with if you feel you need a different food.
I use the vigorous belt from lvl 1 to about lvl 10-12 or so, then switch to a doctor's pouch for the rest of the game. I wear rathound leather for the first two quests, then galvanic/laminated/psi/black tacvest with kevlar balaclava until depot A (kevlar tabis as soon as possible). In depot A I am using a Tm headband and wearing siphoner leather armor and siphoner spring boots (for extra acid DT). After depot A stick with siphoner leather/tabis and a TM headband. Upgrade to infused leather as soon as you finish the beast quest; I can't decide if I like regular siphoner or greater siphoner better. They both look cool, and regular has higher heat and acid resist so you have less trouble with ground fire/acid puddles (which can ruin tranquility), but greater has energy too and has a higher quality ceiling. If you don't care about looks, slap antithermic on them for extra heat protection and make them insulated regardless (dont want to be frozen). By the time you get expert sprint you should switch to infused hopper tabis for the decreased cooldown, but keep your siphoner tabis for arenas with slows (like creeper areas or areas with cold gas). I prefer a TM/expanded/muffled headband, with limited temporal increment/dilation/contraction/precognition/stasis/recurrance.
For weapons, I like to use a straight supersteel energy machete (until you get the Red Dragon) with a tichrome serrated energy knife. The supersteel has more precise flurries, and the knife has low AP costs for when your flurry is on cooldown and applies cheaper expose weaknesses (and it stacks up taste-for-blood faster); energy on both because it is less-commonly resisted and won't ruin incaps on nearby enemies. If you want, you can use a tungsten machete with moomoo milk for some serious damage (tungsten shock is good for strongmen and nagas). However, I've found that you dont want to do too much damage too fast with machetes because you don't want your first two flurries to kill until you've got your flurry AP cost down to minimum. With onslaught, taste for blood, and carved-up, your damage steadily increases throughout the battle. You do not need to truly optimize for damage with machetes, and crit chance can easily get too-high; again you dont want to kill too fast early on; in fact I wouldn't pop a focus stim until you've got flurry built up.
edit: just realized that you may also want to leave your weapon uncharged until you have flurry built up
A low/low efficient energy shield is best, unless you're up against plasma beams and plasma turrets, or snipers, in which case I'd use high/high efficient. You may want low/low amplified for certain fights (like deathstalkers or carnifex). Speaking of snipers and deathstalkers; if you're up against stealthed enemies, you can run out into the open and/or make some noise, then enter stasis and let them reveal themselves.
For utilities, I prefer a taser, nets, and flashbangs (you'd think with these and dilation I'd want opportunist, but killing too fast is an issue) or stingballs vs high-resolve and/or low-armor enemies. You could use nail bombs for easier tfb, and plasmas if you feel the need for some AoE damage. I find that plasma grenades are good for killing jet skis, and nets don't work on water anyway. However, you can also use molotovs to set your enemies on fire and create dangerous ground to help corral enemies and keep them off your back which you are almost completely immune to (actual immunity if you make your armor antithermic); with your evasion and armor you just aren't taking damage even from napalm.
For jetskis, get a torpedo and use a tungsten electric spear (with hunter, naval jousting, and high speed/turbo, you're doing crazy damage and jetskis make flurry a little too unreliable). You'll need to use adrenaline or vitality powder to use a tungsten spear without penalty, but you really shouldn't need more than 3-4 turns to win a fight (stasis adds a turn).
(the dodge/evasion pic below is at lvl 25 or 26 with no SSD)
