Lot of people are left wondering if Drk is going to be competitive, given their kit, with the existing tanks. In my opinion, Drk is not lacking power, as much as it is not getting reliable access to its power -- and the issue is that reliability is the name of the game at the moment in endgame tanking.
Honestly, to me, there are two things that need to be changed for DRK to be viable:
1) reprisal need to be accessible in a reliable way, because not having access to it when you want to is terrible for real raiding
2) Drk need a bit of help in the physical side of things; being super good on magical and only decent on physical, and thus a counterpart to pld godly in physical and decent on magical, is fine, but at the moment they are not even decent against regular physical tank busters.
For point 1, i would have two ideas right of the bat. In both case, have the main ability be as it is, except you don't need to parry to activate it, making it reliable even as an off tank. Then, make the trait be one of two things:
-Whenever you parry an attack, reduce the CD by 10 sec
-Whenever you parry an attack, 10% chance to get a buff. The buff last 3 seconds. If you activate reprisal during the buff, it does not go on CD.
In both case the trait ties the ability to parry, as per design, but at least you are not locked into having to parry to use it. The second one is pretty neat lore-wise to function as a "reprisal", and would be super fun. You would keep reprisal ready for the next tank buster, but whenever you are parrying you get a chance to put it up for free, without sacrificing it for the next tank buster. One may want to give it a CD of 15 sec instead of a minute instead of just not using the CD, to avoid abuse of spamming it with a high parry rate, but allowing still one to keep it up if you get a bit lucky.
For the second point, i would tweak dark dance. Currently it function as some kind of bulwark, unreliable. Point being, Drk doesn't have enough stuff to mess around with such things. I would suggest one of two changes:
-Dark art effects: 20% physical damage reduction instead of the dodge
-Dark art effects: increase parry rate to 100% instead of +30% (and remove the dodge too).
In both case, this would turn dark dance into a reliable physical CD.
Given those two changes, which really are mostly "tweaks" and do not add power per say as much as making the existing power reliable, i am sure Drk would be much more competitive with the current tanks.