With Shadowbringers on the horizon, I thought that I would outline some of the main changes that I would like to see on DRK.
Resource Management
The best starting point for revising DRK is to look at the resource system.
DRK relies on establishing a balance between MP generation and expenditure. Most of the changes in DRK's gameplay between Heavensward and Stormblood come from the removal of Darkside's MP drain. This tipped the balance in favour of MP generation. Dark Arts ended up becoming a stopgap to burn off this excess MP.
I think that there should be three goals here:
1. Adjust the rate of MP generation relative to your max capacity. Either you need a slower, more steady rate of MP generation, or a bigger max capacity.
2. Introduce in more ways to burn off MP. This could be through using more off-globals that burn MP, or an alternate combo that either halts MP generation or burns off MP.
3. Create more of an interplay between blood and MP.
For the first point, I'd like to see big MP dumps replaced with more gradual effects. Instead of generating all of your MP on Syphon, you should generate a third of that on every GCD that you perform. Likewise, Sole Survivor could very easily give you the same effect over time, as opposed to dumping 20% of your max MP into your pool all at once 15 seconds later. Delirium's MP dump is another example, but I'll address Delirium later on.
I think the best place to burn off excess MP is through off-globals. If Dark Passenger offered a clear benefit in single target, that would be one place you could be spending your MP. Sole Survivor could be another place you could add a cost, if it had a DoT value as it drained HP and MP over time, as could Salted Earth. Another alternative could be to introduce in another off-global or combo action that burnt off MP, like a MP-powered alternative to Bloodspiller.
But there is another option: rethink how Dark Arts works. What if, instead of activating on the next action which could proc it, it simply lasted for the next three GCDs, boosting every action performed in-between? The caveat being, that while it was active, any effect that would generate MP generates blood instead.
At lower levels, this would just be the equivalent of turning off your MP generation to do more damage. At higher levels, it would give you a way to keep your MP in check to prevent capping, while simultaneously letting you build up blood to perform your more devastating attacks.
Stances
Stance restrictions need to go. Effects that are locked behind Grit might as well not exist. The HP drain on Souleater, and the stance locks on Blood Weapon/Blood Price are all unnecessary restrictions. If balancing Blood Price is a problem, get rid of it and make Blood Weapon universal.
But more generally, stances themselves don't make a whole lot of sense on DRK. You could remove Darkside altogether (or keep it as a trait), and just give DRK an MP system in which they generate all of their MP from GCDs while in combat. Perhaps your connection with the Abyss saps your life force, forcing you to feed off your opponents' Aether.
Defensive stances on all tanks could easily be replaced with a skill that lets you generate burst enmity for yourself.
Defensive Abilities
DRK is in a pretty good place defensively. I personally think that Dark Mind is overkill. A lot of people have talked about how inconsistent DRK is at mitigation prior to level 70. One possible solution to this is to convert the existing Dark Mind into a self-only version of the Blackest Night at level 42, and having it "evolve" into the Blackest Night at level 70.
Living Dead is a problem. The recast is fine, but it needs to be more self-reliant. The easiest solution is this: You hit 1 HP, Walking Dead procs, and for the next 10 seconds, incoming damage heals you for a fraction of the damage that you would have received. This way, it's not as good as simply ignoring the damage, but it also gives both you and your healers a bit of respite when you need it.
The instant death effect is completely unnecessary, and really shouldn't be in the game without both giving the DRK player a means to cleanse the effect on their own, as well as clear UI elements which indicate how much further self-healing is required.
In order to round off DRK's defensive kit, I think there needs to be more of a focus on lifesteal. Souleater should always steal HP. Bloodspiller should steal both HP and MP. Sole Survivor should drain HP and MP over time, with the recast resetting if you kill off your opponent before it expires. Perhaps even Salted Earth should steal a bit of HP, if you add in an MP cost for using it.
Offensive Abilities
DRK's main problem from an offensive standpoint is that Delirium is underwhelming. To the best of my knowledge, it's the only offensive buff that has a resource cost attached. But it doesn't offer anything particularly unique to offset this. It's also finicky in that you have to have Blood Weapon or Price active for it to actually do anything, otherwise it just fizzles out.
I think that the best solution is to turn Delirium into an upgraded form of Blood Weapon. I've mentioned this elsewhere as well, but speed boosts are less straightforward than power boosts. You can't just make Delirium into a faster Blood Weapon. Speed boosts place limits on your off-global weaving.
The work-around to this is multi-hit attacks. While Delirium is active, in addition to the baseline Blood Weapon effect, you could make attacks performed under Dark Arts hit a second time for a fraction of the damage. After all, if your enemy is Delirious, perhaps they're seeing double.
Also, if Carve and Split was actually broken down into a three-fold attack, seeing it hit six times would be pretty awesome.
One more point here: Stormblood's focus on knockback mechanics has shown that Plunge just isn't up to the task. Either we need some form of knockback prevention to preserve our Plunge usages, or Plunge should reset on the player receiving a knockback effect.
Future Directions
I've touched on this elsewhere as well.
As far as new actions are concerned, the main thing that I would like to see is something that builds off of Delirium, as a sort of multi-hit finishing move that you can throw out at the end of your burst window. The most obvious choice would be Cecil's aptly named Shadowbringer (although something akin to Omnislash would do in a pinch).
The idea being, if you're using Dark Arts under Delirium to land additional attacks, you should have a move at the end of the window that gives you an extra hit for every enhanced attack you landed with Delirium active.
Other possible ideas? Celes' Runic Blade could fill in as a means of providing raidwide mitigation on DRK. Dread Spikes is an FFXI DRK ability that could be brought back as well, in keeping with the lifesteal theme. An additional combo action or standalone GCD that burnt off excess MP might be a possibility as well.
As far as removing actions is concerned, there are a couple of abilities that could be overwritten at higher levels. I've mentioned about how you could have Dark Mind be replaced by the Blackest Night in the defensives section. Unleash could similarly be overwritten by Abyssal Drain. Blood Weapon could be overwritten by Delirium. You could easily free up one more spot if you turned Darkside into a trait, and another if you got rid of Grit altogether.
Aesthetics
One of the most common requests on DRK has been for a proper Darkside effect. The main restriction until now was the fact that Darkside is always on. If you traited Darkside or got rid of it, you could easily attach a flashier effect to either Delirium or something else.
Either way, with the amount of times that we've been teased in game with better auras (be it in the Dark Knight quest cutscenes, Hildebrand quests, and most recently, the in Shadowbringers' game trailer), it's high time we got a proper darkness effect.
One more point as it relates to relic weapons. Final Fantasy has a very large number of famous weapons. The vast majority of them, unsurprisingly, are either swords or greatswords. But for some reason, we're still yet to get a truly iconic named greatsword as a relic weapon. ARR gave away some of the most famous greatswords to other jobs, in the form of Ragnarok, Apocalypse, and so on. Since then, for some reason, most of the names have been based on FFXI weapons, which don't have nearly the same widespread appeal.
I would love to have Save the Queen as a greatsword. And not as a weird, pseudo-cutlass with irregular spikes. A nice, oversized, clean greatsword. Like what you see in the trailer.
Either way, we'll see what's in store in about a month or so.