I just finished playing through insane on a skeleton shadowblade loosely using this guide. Figured I'd give my thoughts on the class and build (as of game version 1.5.5). Before I begin, I first want to give a big thanks to Zesty Crab Legs for his guide, even if I disagree with a few points.
Disclaimer: I used an addon to choose which escorts I was offered, and while escorts aren't a requirement for the build, they're definitely a big help, especially on insane difficulty. I also use an addon that lets me fully respec my talents, which is how I was able to swap up the build without having to entirely reroll. I consider these addons quality of life improvements, but someone could argue it's "cheating". To each their own.
First of all, the basic character building choices I went with as a Skeleton are:
The talents can be seen here: Click Here for Image
Stat Priority: Dex -> Cun -> Mag -> Con
Prodigies: Spine of the World (lvl 30), and Arcane Might (lvl 42)
--Temporal (lvl 10)
--Inscription (lvl 20)
--Temporal Enhanced +0.2 (lvl 36)
--Combat Training Enhanced +0.2 (Wyrm Bile)
Alchemists: Focus (+2 class points) and Foundations (+2 generic points) are important.
--Dex/Cun, Mag/Will, and Str/Con would be the extra potions.
Escorts (in order, if you choose with an addon or save scumming):
--Anothoril: Healing Light (rank 1) - This is near worthless lategame, but it makes the early game so much smoother as a skeleton.
--Warrior: Vitality (rank 1) - Mostly for the disease reduction, as skeletons are immune to poison/bleed anyway.
--Warrior: Unflinching Resolve (rank 1) -- At 5/5 this lets you frequently break stun, blind, confuse, and pin. Excellent.
--Warrior: Unflinching Resolve (rank 2)
--Warrior: Unflinching Resolve (rank 3)
--Warrior: Unflinching Resolve (rank 4)
--Warrior: Unflinching Resolve (rank 5)
--Thief: Heightened Senses (rank 1) - Free generic point
--Thief: Device Mastery (rank 1) - Free generic point
As for some comments on each specific talent:
--Dual Strike 5/5 - I found maxing out this was helpful for the duration boost, especially for enemies that flee
--Flurry 5/5 - Hard hitting attack, maxed for damage
--Rush 1/5 - Backup gap closer when Shadowstep is on cooldown
--Precise Strikes 5/5 - Huge crit chance and accuracy bonus for a negligible drop in our huge attack speed
--Dual Weapon Mastery 5/5 - For the damage bonus
--Tempo 5/5 - Maxed to replace the stamina loss from Trained Reactions lategame
--Nothing here: I used these early game, but I found that on insane, enemies detected me no matter what, so I found stealth to be almost worthless aside from the crit bonus for the first few rounds of combat. I eventually ended up dropping this tree entirely.
--Dirty Fighting 1/5 - As a prereq, but also to lower debuff resist on some bosses
--Backstab 5/5 - With your stun and some debuff procs from gear, this should always be active on hard enemies
--Lethality 5/5 - More damage, and lets you ignore strength entirely (skeleton racial covers gear requirement)
--Expose Weakness 5/5 - I maxed this because lategame the only thing that was a challenge was bosses with huge resists, and this helped.
--Shadow Combat 1/5 - Prereq only, this skill is impossible to sustain, don't activate it
--Shadow Cunning 5/5 - More spellpower means more damage (arcane might) and survival (time shield)
--Shadow Feed 5/5 - Mana regen and attack speed, obvious pick
--Shadowstep 5/5 - Max this for the range increase, since teleporting mages are a headache. Our best skill IMO
--Congeal Time 1/5 - Prereq, we're not a real caster
--Time Shield 5/5 - Amazing skill that adds huge survival and debuff mitigation. Max it.
--Time Prison 1/5 - Another prereq we never cast
--Essence of Speed 5/5 - Always active +53% global speed by endgame. Amazing.
--Thick Skin 5/5 - Awesome for mitigation. Carry +con gear to max it easily
--Heavy Armor Training 1/5 - So we can wear metal accessories
--Light Armor Training 5/5 - Added survival, reduced fatigue costs
--Combat Accuracy 5/5 - Accuracy is what determines your debuffs like stun landing and their duration, you want as much as possible.
--Dagger Mastery 5/5 - More accuracy and raw damage, max this
--Disengage 1/5 - Mostly as a prereq, but sometimes has a use.
--Evasion 1/5 - Added survival, I had this on auto-cast when enemies are in melee range.
--Tumble 1/5 - Prereq only, I didn't like the debuff this gives so I never used it.
--Trained Reactions 4/5 - Great for survival, but very expensive to maintain. By endgame with Tempo and 100% crit, you can leave it on.
--Heightened Senses 4/5 - Helps see invisible mages even at long ranges.
--Device Mastery 1/5 - Prereq, but helps your trinkets some at least.
--Track 1/5 - Useful to scout, could skip this and device mastery if you have another source of Track.
--Skeleton 5/5: Dex is great, and the Str lets you wear your gear.
--Bone Armor 5/5 - This shield is huge with your high dex. Simply amazing.
--Resilient Bones 5/5 - All debuffs are cut by 44% duration. Need I say more?
--Re-Assemble 5/5 - Your big heal on a short cooldown
Be warned that this build is a late bloomer, and the early game, especially on insane, is VERY challenging. Low defenses, and vulnerable to debuffs. It's going to be an uphill battle for the first 30 levels, especially as a skeleton with a big exp penalty.
That being said, once you hit level 30 and get your first prodigy (Spine of the World), then that combined with your other defenses that are coming online like Time Shield, Resilient Bones, and Unflinching Resolve (escorts), and you can almost entirely ignore debuffs since at most you can get inflicted with one debilitating physical debuff per 5 rounds, and you either break out right away from resolve, or the duration is reduced to one round, maybe two (time shield, resilient bones).
By the time I got the second prodigy at level 42 (just as I started the Far East I think) my damage had progressed to the point I was one shotting almost everything except rare+ enemies, and with our long duration stun combined with our extreme accuracy, any non-immune bosses were frequently stunlocked.
Lack of AoE wasn't really a problem because between Time Shield, Bone Armor, Re-Assemble, and Lifeleech I could sustain long combats while one shotting huge packs of trash. Once you come back from the Far East, try to get a dagger from the artifact merchant with the property "Projects up to 3 attacks dealing 30% weapon damage to enemies within range 7 on hit" (always active 100%). Once I bought that weapon, it makes everything you do AoE, so big packs just melted.
This class was loads of fun, and it felt like god-mode by the time I hit level 45'ish, but I really have to stress that this is a total late bloomer. The early game was like pulling teeth, with lots of running away and retreating to previous zones, etc.
Thanks for the initial guide, which influenced me to try this class.