Skills - Full scale rework of VW's Mark mechanics

[Goliath]

Preface
Void Walker barely brings any new power to a Pariah. Cheaper movement and improved out-of-combat hiding are nice utility quirks but they aren't particularly strong on a class that doesn't have any non-combat strengths (say better searching or barricading). Whatever combat strength it gains is gated at huge MP costs for a Pariah's tiny regeneration and MP pool, and is rarely better than just dropping charged attacks.
Basically, a VW is a Pariah who can walk and hide for cheaper.

Utility Skills
They're a nice extra touch. Nothing that carries the class, but VWs don't really fit a utility archetype, so that's fine.

Strangulation
Getting this and focusing on the utility skills seems like a viable build. Could maybe even synergize with the Stepping stance. It pretty much screams "Enervate+Rend Flesh", which adds to its MP cost.

RANT AHEAD
Mark of the Assassin
The biggest issue with the class. Its only offensive gimmick, which comes at a very steep 5 MP cost per target for a class that's rather MP intensive and starved. Their stances would be really nice at adapting to any target if that didn't require 5 MP to swap stance + 5 MP to mark the new target, too. Currently, the stances don't offer much in terms of choice, either.

• Stepping of the Assassin: Tank-busting stance. Ignores enemy aura. Would be great against tanks if using it didn't mean not using any aura that'd let you damage them. (0/20 pick rate*)
• Precision of the Assassin: Tank-busting stance. Decent against Infernal Behemoths, heavily outclassed against everything else. (0/20 pick rate*)
• Assassin's Edge: Tank-busting stance. Absolutely great at shredding tanks once you invest 180 CP on this + Creeping Chill. Only workable with a bow -- forget about Strangulation, you don't have the CP for it anyway. Personally, the only that warrants the MP used for marking against appropriate targets. (4/20 dank rate*)
• Cruelty of the Assassin / Strike of the Assassin: Damage-oriented stance. Not as great at tank-busting as the previous, but its upgrade seems great to expedite kills. Most targets you can kill with this can be as efficiently killed with an extra Hellfire shot, though. (7/20 and 3/20 pick rates*)

* Pick rates are against the total users of Mark, not against total number of VWs

Bow of Frostbite/Chill Sniper
MP intensive innate in already MP intensive class. It'd be great otherwise.
Effectively, a 90 CP tax to use Bow + Assassin's Edge without blowing your AP to hide.

Void-touched
Being able to ignore glyphs of slowing is neat. But the cost to bypass a glyph of slowing is huge, and significantly higher than casting a learned GGE from a spell gem (both in terms of MP and CP). It also does nothing for your allies in raids, nor protects you from glyphs of sapping which empty your already shallow MP pool. Overall, this is worse than an actual GGE in both cost and usefulness.

[Goliath]

To preserve the rough structure and effects of Mark and its child skills, I'd opt for keeping the Mark/Stance skill tree structure, and the stance-dependent mark effects, but would add a base effect to stances to make them useful without needing to spend 5 MP per target. I would also give each stance a clearer focus, and possibly reduce their number.
Given the VW doesn't have much offensive power elsewhere, I'd make each stance have a 60 CP base form and a 90 CP upgrade, to justify these being rather strong.

Reworked Mark of the Assassin
For 5 MP, the Void Walker may target a foe for assassination and gain +1 damage against the target.
The bonus damage increases to +2 if a Stance is active, and to +3 if that Stance is upgraded.
Only one stance may be active at a time.

• Cruelty of the Assassin
  Damage stance. You gain the bonus damage from Mark of the Assassin against any target, doubled against Marked targets.
  • Strike of the Assassin
    You execute targets who fall to or below 10% HP after you damage them. You get a chance to critically strike against Marked targets, doubling the damage from Mark of the Assassin again (for a total of +12 damage). You always critically strike from hiding.
• Lethality of the Assassin
  Tank-busting stance. You take half damage from auras and rebound effects (such as Acid Blood). You ignore half your Marked target's soak.
  • Precision of the Assassin
    You take no damage from auras and rebound effects (such as Acid Blood), and half damage from retaliation attacks. Your attacks against Marked targets always strike true, dealing half damage if missed or phased.
• Intuition of the Assassin
  Hunting stance. You gain 10% defense, and you take half damage from pet retaliation. You can Mark a nearby target outside a Stronghold, and can tell their direction.
  • Bloodthirst of the Assassin
    You heal for 5 HP every time a character on your tile dies, and you deal increased damage to pets. If your Mark's target dies within 5 minutes of being Marked, you recover its MP cost.