Only after i figured out this build, i realized that it really reminds me of Ghost units in classic Starcraft - stealthy snipers who are also able to cast "spells". Hence the name. And, this build is the most powerful sniper build, and possibly the most powerful build of them all, which i know of.
TL;DR: get Strafe, Interloper, Ambush, Tranquility, Psycho-neural Flexibility, Premeditation and the usual sniper feats; innervate Thermodynamic Destabilization, Telekinetic Proxy, Electrokinetic Imprint, Psycho-temporal Contraction, and any 2 of: Cryostasis / Limited Temporal Increment / Stasis. Use Dragunov and later high-quality crafted Spearheads for 0% Move and Shoot precision penalty, and some 8.6 / 12.7 rifle for hard-hitting while Focused. Use said psi abilities to make huge explosions whenever there's a pack of enemies, and then crowd control and set up Ambush targets if/when needed.
Now in some detail.
Main idea is simple: to fix three main weaknesses, which sniper builds usually have, via psi abilities which do not require high/maxed psi skills. Namely:
#1: snipers got no AoE damage potential (other than things like frag grenades, which are available to any build) - unlike pure psi / AR / SMG / shotgun builds, which all come with strong AoE damage features. Thus, snipers often get in trouble against large packs of enemies. This build solves it by using Thermodynamic Destabilization on highest-health target in the pack, which at 140 effective Metathermics skill - deals 100% of that target's health as an explosion upon its death. With Tranquility, it's just 5 AP to cast, and has range of 10; and with Premeditation it's 0 AP and range of 13 - almost as far as a sniper rifle shot. This gets to 11 / 14 range with a certain late-game outside-levelling feat, too. If some targets survive the explosion, usually they are so weak a single grenade and/or few shots with a side arm finishes them all.
#2: snipers do high bursts of damage (Spree / Snipe / Aimed Shot) and then spend a turn or two being not-so-deadly. This build solves it by controlling any remaining enemies with Imprint, Cryostasis and/or self-cast Stasis. Having at least two of these innervated, and if need be all three, allows huge amount of crowd control. I.e., whenever needed, fall back behind some corner and have incoming enemies stunned / frozen, and/or Stasis ourselves, to get Aimed Shot and/or Snipe available again. For the latter - Snipe - having any single remaining tough enemy frozen allows to reenter Stealth easily. Very convinient. Most of the time, none of it is needed - but it's exactly longer / harder fights, which are few, which sniper builds struggle with; but not this build.
#3: sniper rifles come with high move-and-shoot precision penalty, which usually makes it impossible to have full accuracy whenever there's a need to hide behind some corner during any prolonged battle (e.g. expedition camp defense battles). Using Strafe feat (and having stats required for it) with 7.62 sniper rifles solves it completely, while freezing / stunning enemies and using Stasis on oneself often allows to avoid the need to hide behind a corner to begin with. The latter allows to use heavier sniper rifle for its full potential for more than just 1st turn of combat, while the former serves as "plan B" whenever enemies are too many, or would shoot with crossbows / sniper rifles from out of line of sight, or simply unknown number / location, so it's safer to just hide behind something and peek out each next turn to hit them.
Stats:
STR 4 - sniper rifles require 5, yet this build gets +1 Str from Rathound Regalia armor (i go for it right after Depot A and use it ever after), thus no need to get 5 Str with hard points;
DEX 5 - for Strafe feat. Not negotiable: being able to have full accuracy after hiding behind some corner and peaking out to shoot - is just too good. Also, gives bonus points to some useful skills;
AGI 7 - for Interloper and Sprint feats. And extra Stealth effective skill points, which improve Ambush crit chance, Snipe damage, and simply allow to sneak around better / easier.
CON 3
PER 10 > 18 - for sniper feats and maximum damage from maximum possible Guns skill. OP detection and overpowering enemies' Evasion are the usual QoL things too, ofc;
WILL 3 - synergies between 3 different psi schools nearly cancel -10% penalty for effective skill points, and we're not maxing any psi school, too - only need specific, not so high, values;
INT 8 - for 6 psi slots. Wish it could be 7, but not enough stat points to go Int 10 with all the above. Also, 8 is required for Psycho-neural Flexibility, and gives good amount of bonus effective skill points to many useful skills.
Feats:
lvl 1 - Aimed Shot + Sprint
lvl 2 - Tranquility
// this early in the game, Cryokinesis with its native 100% to hit and long range is pretty useful even at 3 Will, and Tranquility much improves it; and 5 AP Cryostasis for emergencies is nice
lvl 4 - Strafe
// sniper rifles get good a while later - not at level 4 - but there are other important feats to take at lvl 6+, so get it now
lvl 6 - Ambush
lvl 8 - Snipe
lvl 10 - Shooting Spree
// should be going to grab Dragunov sniper rifle before or near lvl 12, at which point proper Sniper times start
lvl 12 - Premeditation
// 0 AP for any psi ability, halved psi cost and +3 range, all together - is just too good to skip
lvl 14 - Blindsiding
lvl 16 - Critical Power
Feat specializations:
- i think it's best to get Shooting Spree 1/1 1st, then 10/10 Critical Power by lvl 26;
- remaining 4 specialization points at lvls 27...30 - personal preference; good choices are:
-- 4 spec points into Interloper, which means 24% stealth speed penalty instead of 30%, and more importantly - 23 movement points in stealth instead of 15, which MPs are real handy when peeking outta some corner in re-entered Stealth to make another Snipe hit; or into
-- Aimed Shot - extra 20% crit damage bonus of it gets multiplied by both high Guns skill and +special-attack bonuses from Goggles and Smart Module in our crafted sniper rifles; or into
-- Shooting Spree cooldown reduction, if really bothered by its rather long cooldown.
lvl 18, 20, 22 - Interloper, Psycho-temporal Acceleration and Psycho-neural Flexibility in any preferred order (i prefer this one);
lvl 24 - anything desired, e.g. Pack Rathound
lvl 26 - Increased Perception
lvl 28 - Advanced Psi Empathy
// this feat is usually not available for sniper builds, but this build got 100+ hard-pt Metathermics. -20% psi costs is really big, and by lvl 28 extremely strong crafted shield emitter should be in use, plus health pool is quite high despite Con 3, because of being this high level - so health reduction is of very little concern
lvl 30 - anything desired, e.g. Sharpshooter
// note that Sharpshooter does not work whenever we shoot after we've moved during any given turn, which is why it's optional and least priority for a Strafe-based sniper build
Essential skills
Guns max
Stealth max
Metathermics > 140 effective ASAP
// including synergy points from other psi skills. This means 142...143 hard points invested in Metathermics;
Psychokinesis > 55 hard-pt ASAP
// required for Telekinetic Proxy, which is absurdly good to promptly light up targets for Ambush shots; and 45 hard-pt required for Imprint, which beats often-praised Quick Tinkering feat fair and square: much shorter cooldown, much lower AP cost, and is a ranged ability unlike traps which require being next to the tile being trapped;
Temporal Manipulation > 70 hard-pt after getting 55 in Psychokinesis
// 70 needed for Stasis, and lower amounts for other useful TM abilities
Mechanics > ~90 hard-pt eventually
// exact amount depends on how convinient one wants to be about crafting high-end (150sh...160sh) guns: whether to use Hypercerebrix to do it or not, Jon's Special or not, waiting for Your House +15% bonus or not
Electronics > ~100...110sh hard-pt eventually
// same reasoning as for Mechanics. Crafting high-quality goggles with high damage bonus for ranged weapons special attacks - is a must have. Plus, high-end dual-emitter energy shields require 180sh effective skill, and highest i remember i made - even required 203 effective Electronics. Yet we can get +10 from Phreak glove and +10 from Lemurian Engineer suit, which bonuses then become +23 to effective skill value with +15% bonus from Your House bench. And this build gets +51% to hard-pt Electronics when buffed by Hypercerebrix (so 10 Int). E.g., if having 100 hard points in Electronics, with Hypercerebrix, Your House bench bonus, +3 from food buff, and +20 from said items equipped, effective Electronics will be: ( (100 * 151%) + 20 + 3 ) * 115% = 200.1, i.e. exactly 200 effective skill. A bit higher than 100 hard-pt - is just convinience and/or not willing to murder Phreak for the glove and/or not waiting for Lemurian Engineer suit.
Skill points remaining for non-essential skills by lvl 30: 1200 - 2x160 - 143 - 55 - 70 - 90 - 100 = 442. This is a lot to get plenty other good skills for quality of life / extra combat utility. One of possible setups:
- Throwing effective ~100: hard-pt 92...93 with Dex 5. This allows to do 90% accuracy grenades at ~5 tiles;
- Hacking effective 130, for passing all Hacking checks in the game: hard-pt 65, then Hypercerebrix (130 skill checks are real few), with +20 from items, +10 synergy and +3 food;
- Lockpicking effective 130, for passing all Lockpicking checks in the game: hard-pt 67, multiplied by 134% with All-in food buff (thus 8 Dex), with +32 from items and +9 synergy on top;
- Mercantile effective 105, for unlocking all special vendor inventories and price reduction in shops: hard-pt 68, multipied by 134% (usual 8 Int), with +15 from Large Waist Pack;
- Biology ~40 hard-pt: allows to craft Hypercerebrix with all the obtainable bonuses - needs 70 effective, on top of crafting Toxic Gas Grenades, Adrenaline Shots, etc;
- Chemistry ~30 hard-pt: effective 50 to craft W2C ammo, 45 to craft Cryo Gas grenades, 40 to craft mk2 Incendiary grenades (light-weight, great to light up large areas for Ambush shots), 20 to craft Toxic Gas grenades;
- Tailoring / Persuasion / Pickpocketing: 80 remaining hard points can be spent into one or more of these, whichever is liked most. Maybe even some points into Traps if enjoying using them (alas, this build does just fine with very little trap use - other than staple bear trap abuse in select few battles, like Expedition Camp defenses). Tailoring is of little use for this build: a bit higher-quality Ninja tabis can be crafted than what Constantine sells (he sells up to 2400 durability, which is roughly ~142 quality Black Cloth), while all other item slots are non-tailoring gear. Or, if to squeeze an extra hard point somewhere else - these last 81 hard points can go Pickpocketing if going for an Oddity run, which with 5 base Dex + All-in + Supersoldier buffs will even be enough to see Ethan get old: 82x151% = 122, and that's exactly how much Pickpocketing is needed to steal his thing.
Couple ending notes which may come handy.
This build is also able to do easy silent assasination of any - however tough - single target, even ones like Balor, by doing this: sneak in, start combat manually, cast 3 Cryokinesis (noise = 5, practically silent) and then Crystasis, this freezes 'em for 5 turns; then drop Toxic Gas at their feet same or next turn and wait for them to get +200% damage taken debuff; once they unfreeze, finish them off with either more Cryokinesis hits or burst fire from silenced 5mm SMG. The latter, with highest Guns skill plus W2C or Shock ammo depending on target's resists, becomes extremely deadly with +200 damage taken debuff, wildly exceeding damage tresholds of even heavy armor - even without any SMG-specific feats.
This build, late-game, much enjoys using AKX as "smaller sniper rifle". The gun's indestructibility is sure nice; it can hit anything within usual sight rage, has very low single fire AP cost in compare to any proper sniper rifle, and then, with most feats taken, Guns skill at 300+ and ~100% crit chance for Ambush shots - does some 200...300 damage per crit against most foes. Excellent for dealing with survivors after Thermodynamic Destabilization explosion, if there are any.