See how bad it is? Khornates have turned into ambush class. Khornates.

I've always played pure Khorne wherever i could - TT, videogames. Which oftentimes resulted in getting my ass stomped by more versatile armies in TT, especially in 3.5 edition lol, but hell man...it was fun. Khorne is Khorne.
I really, really tried with EC, but MoK was just straight up unenjoyable to play :[ so sad. I havent gotten the Manslayer yet so ima run some builds with it once i get it; for now Nurgle builds feel the best to me when it comes to melee.
Only thing relatively good about MoK right now is the voice acting (which is so-so but still better than that weird deep as hell tone they picked for Slaanesh, so unfitting for a God of hedonist narcissists; should've made it more subtle and menacing).

You had me at the first sentence.

I think instead of automatically giving Nurgle Marines posion melee, just make the Plague Knife slightly cheaper, it already requires the MoN and the mark is easily one of the best.

MoS could probably have OPs suggestion that's fine. But also just think of how useful it actually is to have speed on a dev class in a team setting. It doesn't stand up as well in a defense, but on offense MoS can set up faster and faster than MoN the further the running distance. Plus @Valnak is wrong. There has to be god-locked items. Blastmasters and sonic weapons that "make MoS worth it" are yet to arrive, and can only be gifted to followers of Slaanesh. MoK would never use them, just as MoT would never wield a plague-knife or a MoN use arcane bolts.

MoK should trade armor for hp so their self healing has more effect.

Executions should grant a stackable Embolden effect called Bloodletting to all nearby MoKs. Every time a MoK executes an enemy, he effectively casts a red hued Boon of Change directed over his head that stacks up to 3-4 times. This effect casts immediately upon pressing E, to grant at least a bit of damage resistance. It ONLY affects MoK because it's not sorcerory. It's visible anger. If you remember, Embolden when stacked not only provided reduced damage taken, it healed over time.

Which I think solves the problem because MoK is essentially plays like a high risk gambling without much reward and very, very little sustain. You start small - assassinating and murdering 1:1 if you have to, but once you get rolling and covered in blood you become more and more of a juggernaut.

Lose, you lose it all.

And that again is why each mark should retain a drawback. It's essentially drawing so much power from an aspect of Chaos, it sickens or neglects another area. This is the essence and lore of Chaos at work, it's about extremes - not just the devs balance scheme.

For example MoT trades hp for the best armor regen in the game. (Enhanced flesh for a step closer to rubric marines).

MoN trades stamina regen for some of, if not the best resiliency. (diseased hulks)

MoS trades speed and mobility for Armor regen - making them "feel pain" for as long as possible. (SM Dark Eldar.)

MoK trades healing and a downed state for self regen. (Magic hating in your face Berzerkers). High casualty rates are common on TT.

In cases we see where this works. In others we see where it needs help.

But that gets to the point. If you aren't interested in sacrificing something by making a pact with a God to get power, don't take the mark, choose to serve Chaos undivided - you can still get aspects of these other gods through lesser trinkets.

Your "Embolden" idea sounds a bit complicated, but other than that the whole 'Chaos=risk/reward' thing i do agree on. It should be assymetrical and it should be...well, fun, whereas right now its sort of mediocre.

In my opinon
I think the marks should have an increased cost by 50lp with better benefits and sigils should be changed so as to provide even higher benefits with higher downsides as you become more dedicated to the dark gods and I personally would rework them as follows.

MoK: I think the downside of no healing or downstate is perfect for this mark but I would add more base lifesteal to the mark and the ability to keep fighting as normal after being downed for a set amount of seconds.
As for the sigl keep the lifesteal and ability to fight after death however the duration is longer and you could potentially revive yourself with enough damage output or by performing an execute on a downed opponent.

MoN: Change the downside to lowering the movement and traversal speed of the user by say 40% for the mark and 60% for the sigil.
The mark would provide the same toughness along with a passive % health regen per X seconds (which can potentially revive the downed user if given enough time).
The sigil would provide increased toughness, even higher % health regen and upon the user being downed would release a cloud that both poisons enemies within and heals allys on a moderate cooldown (e.g a cross between the ork poison grenade and the LSM healing gas grenade that is less effective than both of them in their respective fields)

MoS: keep the downside for this mark the way it is currently and increase it for the sigil moderatly e.g armour regen and dely could be slowed by 70%
For the benifits of this mark I think the lower the users health the faster they should perform all actions except capturing objectives e.g reloading, reviving, moving, melee swings and charges.
The sigil should have this effect apply half of the full benefit as soon as the amour is broken and allowing the effect to increase 50% further.

MoT: Honestly I think this mark is fine the way it is it applys a good buff for its downside and I dont think it needs to be reworked but to keep it in line with the other more expensive marks I would add the change that the 15% of your health that you loose gets added to your amour to justify the cost increase.
For the sigil the health loss / armour gain should be increased to 30% while also giving all damaging attacks a small heat build up which can stack with other ailments.

lastly I think the idea of an undivided mark is a good one and should give a minor increase to armour/health and potentially toughness (e.g like 15 to each) and only cost 150lp meaning that high cost builds still have options outside the four main marks.

Overall my reasoning for these changes is that chaos should have to make the descison "do I go for these new more powerful marks while forgoing either a consumable or a grenade (or both), or do i choose undivided and play more traditionally" making chaos as a faction more distinct in both aesthetic and gameplay in comparison to their loyalist counterparts.

I apologise for the length of this post but this is my opinion on the matter and I am more than open to critisism.

always up for challenge no matter how weak khornates are in EC will always be one but yes MoK needs major rework ..

I actually love the idea that MoK gives you some type of Embolden buff if you execute someone. Maybe 10% damage (range and melee), attack speed (melee only), and move speed (run and basic move) that lasts for 15s and is stackable. Each point of stack lasts for 15s. When the execution is finished, you gain all your life back.

This means if you get a bunch of executions in a row, your pretty powerful for like 5s, but the best your going to get is, at best, +30% for a few seconds. Heck, having just a bit more attack speed and damage for 15s is pretty nice, along with healing you.

You can easily show the Embolden effect on a player by making their eyes glow reddish orange along with leaving a Khornish (sp?) glow with their weapon swings to show they are frenzied.

Also, get rid of the odd "reload" sound it makes when you life drain. That shit gets old quick!

If we wanted to add more viability to Mark of Khorne without massively overhauling the whole thing, we could always have them be resistant to enemy sorcery. Not sure exactly which spells that would effect, but certainly Jinx. Perhaps more value to do that once Librarians and Weirdboyz hit.

Not trying to be a TT nerd here or anything, but that would be a bit over the top...Collars of Khorne and similiar toys are what gives resistance to psychery/sorcery, whereas the Mark of Khorne only makes one more capable in close combat.
But then by that logic MoK is weird already because lifeleech? What?
At least the other marks are relatively coherent with what goes on in general Lore and TT.

@SniffSteven
I'd always go for gameplay over accuracy. It would make Khorne-affiliates at least a good sorcerer hunters, which seems quite appropriate. But yeah, I don't think there's enough psychic powers going about it the game right now to make such an ability worthwhile.