Greetings, I wrote this post for sake of providing some feedback in regards to the current state of DK’s in SL. I usually spend some time browsing through the forums and I kept observing the same complaints from various users who simply like to have fun while playing their DK. I am writing this post to provide constructive feedback and perhaps help the devs for some rework ideas, if ever possible.
Before I start, I must point out that the Acherus DK community in discord is a great place for all death knight players who would like to ask questions or learn more about their class or even theorycraft together. Huge shout out to Acherus.
I will divide this post to two sections; PvP and PvE. Under the PvP section I will first focus on Frost then transition to Unholy. For the PvE section, I will first focus on Unholy then transition to Frost.
1.PvP
For PvP, I will focus on arenas. The state of DK in Shadowlands PvP is a bit mundane. Since the start of S1 and S2, most players quickly discovered Frost plays better into comps compared to unholy. Although the recent buffs to unholy (NW duration increased to 15 sec, fallen crusader no longer nerfed in PvP) may have created some opportunity for experimentation, I would like to focus on what most players are complaining about and provide my own thoughts regarding the issue.
1.1 Frost
Frost in arena had Heartstop which would bring a very potent mechanism into pvp. While it is true heartstop was annoying for the opponents, the new abilities that were granted to Frost does not provide the same effectiveness/benefit of heartstop.
I have noticed in various posts that players also complain about chill streak in PvP and request more ST gameplay rather than relying on CS setups which may be easily countered via fade, grounding, leap, disengage, etc. etc. At the start of legion, chill streak had 15 yards range rather than 6, it bounced really quickly between targets while creating insane pressure because each bounce was 8% of target’s total hp (source: Wowpedia hotfix log date 2017-01-17). In general, there must be a risk & reward mechanism which should feel satisfactory to players. If you are risking your damage rotation and going for a setup, and if you performed that setup correctly, the reward should feel satisfactory. Nowadays, you can pretty much see teams not even properly popping CD’s and surviving chill streak setups because it is not as punishing as it was before. Therefore, a setup oriented frost should have more tricks than chill streak. While we have abomination limb + Absolute zero + death’s echo, these tools are usually present to help setup CS, a nerfed 45 sec CD ability. If frost ever moves toward a setup based spec, then there must be another ability which may bring more pressure and shake things up for the next grip + stun. This can simply be a new talent or a pvp talent potentially interacting with remorseless winter or creating something entirely new. Alternatively, Chill Streak can be reworked into an ability based aura which applies to enemies within a 10 yard radius of the DK, and this aura could cause enemies to lose 5% of their HP every sec for a total of 5 seconds (with a proper ability cooldown ofc). This change could prevent teams defensively to cheese only 1 defensive CD and break the chill streak bounce, and it will immensely punish teams which use no CD at all. This would also prevent scaling issues (so blizzard would not need to nerf chill streak every major patch).
For a more ST oriented Frost, we could have a PvP talent which can extend the duration of Pillar of Frost. This change would reduce the counterplay effectiveness of disarms and CC’s during pillar setups since most teams can simply use omnibar addon and reply with a CC when they see the frost dk popping pillar. Alternatively, a pvp talent can be introduced to further reduce the the cooldown of pillar of frost (yes looking at you Icecap but not with critical hits. Frost strike should reduce the CD so our spender should have a meaning). The alternative is to flat out buff damage of frost strike or obliterates so Frost DK’s have more punishing fillers or spenders. I personally favor more CD based approach for balancing issues.
Defensively, new pvp talents can be added which can make IBF apply a self healing, or Death Strike to apply a shield (like how blood dk works) so DK’s can have more response to meleecleaves. Since players can currently select only 3 pvp talents, my suggestion is to rework the Frost DK level 40 talent row. Make Wraith Walk simply baseline and remove it from talents (this goes for all DK talents tbh). Permafrost should be changed to Deathstrike granting a % shield (Casting Death Strike now grants you Frost Shield, a shield equal to 5% of your max hp) and IBF self healing should be added to the middle in place of Wraith Walk. Death Pact should heal for 25% hp without any absorbs or drawbacks.
In essence, the setup oriented frost needs an additional ability other than Chill Streak and the ST/burst frost needs longer uptime + pillar duration. Feel free to add your own intake and feedbacks. In addition, there are some great DK players out there who I am sure will have great suggestions (if they are not tired of trying to offer suggestions).
1.2 Unholy
Unholy was designed to be that consistent pressure class which would eventually rot enemies and win the game. With the introduction of the wounds system in legion, unholy felt fresh and was generally viable in arenas. However, the GCD changes that came years later caused unholy to suffer deeply from the GCD and spell que’s. I personally like the new Necrotic Wounds absorb system which is flat all healing % absorb, compared to the old necrotic strike absorb, which had bad scaling issues and became a joke to delete with a hot. However, I do not think Necrotic Wounds should be based on wounds but rather the solution should include the integration of a long awaited ability (death coil) into Necrotic Wounds (rename to new talent); Necrotic Coil. Most players were really hyped about Necrotic Wounds and Doomburst and imagined a consistent pressure class to emerge. The fact that Doomburst relied on Sudden Doom procs caused players to quickly lose interest and focus only on Necrotic Wounds. For pvp, unholy should not need to apply festering strike or somehow the wound system should be made more rewarding because festering strike consumes too many runes, hence limiting unholy from using abilities such as chains of ice while also suffering in the GCD que. I offer two suggestions: 1) New PvP Talent Necrotic Coil, 2) New PvP Talent Might of the Necromancer. I will first focus on #1 necrotic coil: Your Death Coil applies a 15 sec aura (maybe change to 10 seconds) to your enemy, which absorbs 30% of all healing received. Cannot stack and cannot be refreshed (of course undispellable). This pvp talent can help integrate death coil into the equation because Death Coil is usually a very underperforming ability in PvP. During legion, there was a period where unholy simply ignored even free Sudden Doom DC procs because it was negative DPS. If death coil can somehow be baked into the equation, not only you will have a punishing runic spender which can basically cause enemies to truly ROT and die, but also you now improve your player agency. Will you use that 40 Runic Power to create pressure or will you use death strike? Before you even say it would be op, just look at arms, ferals and other classes with healing debuffs. In addition, this change would punish bad players if they spam DC on the same target. A bad player can make the aforementioned mistake and waste that 40 RP within the 10-15 sec window on the same target whereas a good player can track the debuff and use a free sudden doom proc to apply the debuff on a secondary target. This opens up a new dimension and gameplay completely. Alternatively, the Necrotic Coil new PvP talent can be made as a stacking debuff, ie: Your death coil now becomes Necrotic Coil, which applies a stacking healing debuff on the enemy target absorbing 10% of all healing received for the next 10 seconds per stack. This effect can stack up to 3 times, stacking the effect does not refresh the duration. This alternative would require the DK player more organized runic power management and it would make deadliest coil legendary compete vs frenzied monstrosity in PvP. The #2 suggestion Might of the Necromancer (rename to w/e) tries and improves the wound system: Your apocalype’s cooldown is reduced to 45 seconds and apocalypse now deals increased damage for every wound on your target, up to 6 wounds and grants you Might of the Necromancer which summons an abomination to fight by your side (raise abomination baked together with necromancer’s bargain). Players can synergise Bursting Sores with this talent and create big Apocalypse setups where they can really do some bursty damage. Players can alternatively take Necrotic Coil Together with the Might of the Necromancer and then maybe equal the pressure level of other certain classes.
The Unholy defensive row can also be reworked by making Wraith Walk baseline and adding the aforementioned IBF self healing talent instead of its place. However, Spell Eater should remain.
2 PvE
In PvE, I will mainly focus on raiding but I will briefly touch M+ on a separate paragraph. For raiding, we see a certain Unholy (AoTD) spec and two Frost builds (obliteration vs breath). I have to repeat that there are many great DK players who will have invaluable feedback regarding these issues and I am merely providing my opinion regarding the matter. Feel free to discuss but please be constructive.
2.1 Raiding - Unholy
The AoTD build essentially utilizes the 30 RP Death Coil legendary (Deadliest Coil) to allow the DK have longer Dark Transformation durations, easier lineup of Blight + DT via more death coils. This build usually relies on your army and pet damage, and you try to best utilize your fillers and spenders to line up the CD’s. I observed most players suggesting the Dark Arbiter build from legion or somehow making Scourge Strike / Clawing Shadows and/or other abilities do more damage. In addition, I also observed complaints in regards to the mastery scaling nerf for unholy. While it is true that the build/spec is placed in the middle of the pack and could use a bit more tuning, I personally enjoy the playstyle. However, I think the risk & reward feeling is lacking and this is a common problem with the game. Players do not feel rewarded in a satisfactory level if they pulled off something good. Right now, there are certain classes which can just easily perform without having to go through much trouble (ie lining CD’s observing procs, buffs etc.) If you are designing a class such as unholy, which can really punish a player for misusing CD’s, then the reward should be satisfactory. Someone can say it’s easy to play unholy, but is it really easy to just play unholy or perform as unholy in a mythic difficulty where you have to maintain DPS, track mechanics and coordinate with your raid team at the same time. The problem is certain classes can just perform easily and get satisfactory rewards whereas Unholy feels a bit dull. Since I already stated that I enjoy the AoTD build (feel free to disagree but please be constructive and offer your perspective in an explanatory way), I think the base damage of Apocalypse or some fillers can be improved.
2.2 Raiding-Frost
I was very excited to play the obliteration raiding build in Shadowlands beta. It felt great to play and pumping those big obliterates in the right DPS window felt really rewarding. We then saw some nerfs to obliterate damage and although the build is still played, it is not as effective as Unholy or Breath Builds. I would be very excited to witness obliteration performing in mythic raids. The spec is really good to play and it is punishing if you press your pillar in the wrong DPS window (ie during a dodge mechanic etc). The spec can be reawakened by buffing koltira legendary and or just buffing obliterate damage. Alternatively Pillar window can be increased.
The Breath Build mainly focuses on add cleaves and requires the player to keep breath uptime as much as possible. However as pointed out by Bicepspump it falls short on actual boss damage, which is very crucial in most of the fights. Improving the single target damage potential of breath may offer a slightly better gameplay although I honestly would love to see obliteration build making its way in to PvE.
2.3 M+ Unholy
Back in BFA, unholy with infected claws + bursting sores + festermight build would destroy packs and was really fun to play in M+. The target cap in SL really affected DK gameplay negatively and while DK’s are still okay to play in M+, their viability in SL is nowhere near their viability in BFA. The current unholy M+ build utilizes clawing shadows with unholy blight (3-3-3-3-2-2-1) and resembles the AoTD raiding build if not completely similar. Frenzied Monstrosity is usually preferred in Shadowlands unholy gameplay. In Shadowlands, there are no more mega big pulls compared to BFA. Therefore, with the introduction of target capping and changes to the M+ pulling gameplay, DK’s are at a bit of a disadvantage. The 3-5 target damage of the DK can be buffed either by buffing Unholy Pact + DT or by introducing new talents which can compete vs Unholy Pact in level 45 row. You can also rework Ebon Fever in Level 25 and somehow make casting outbreak viable. Example: Applying outbreak grants you unholy power for 15 seconds, which cause your epidemics and death coils do 15% more damage for the duration. The effect does not refresh or stack. Another suggestion would be to change d&d and make Death and Decay also benefit death coil to hit all targets like SS/CS while the DK stands in it. This change can offer great value during 3-5 target pulls. Alternatively you can remove the target cap and allow for a more effective festering wounds + bursting sores playstyle during death and decay windows.
2.4 M+ Frost
Back in BFA M+, frost was a powerhouse if properly geared. The frostscythe + icecap build with frostwhelp azerite trait would allow DK’s to do massive damage in big pulls and it was great fun to play with. Currently, the frost DK’s in SL are generally using the Breath build to be competitive (source raider.io class/spec rankings). While the breath build can see a buff to breath damage, I personally suggest buffing the remorseless winter legendary and create a new alternative to make the DK player play for high uptime remorseless winter. This change could mainly help with the 3-5 target pulls.
I wanted to write this post and felt like it is already too long, therefore I had to leave out some more ideas, but I would be more than happy to share them if such a constructive discussion environment happens. All the best and thank you for reading (even if you type TLDR 
)
EDIT: I am including the wishlist below to solidify the suggested changes and I will update it regularly:
WISHLIST
1- Frost (PvP)
1.1- Chill Streak PvP Talent Removed.
1.2- Dead of Winter PvP Talent Removed.
1.3- New PvP Talent Deathly Winter: Your Remorseless Winter now reduces all enemy healing received by 5% per tick up to 40% (if you can keep on the target for full 8 seconds basically + Gathering Storm ensures you can stay at 40% for a bit longer).
1.4- New PvP Talent Column of Frost: Increases the effectiveness of Pillar of Frost by 15% and its duration by 5 seconds.
1.5- Obliterate damage increased by 10%.
1.6- Frost Strike damage increased by 10%.
1.7- Wraithwalk Tier 40 talent is now baseline.
1.8- New Tier 40 Talent Iceborne: Your Icebound Fortitude now applies Iceborne which heals you for 40% of your max hp over 5 seconds.
1.9- Tier 40 Talent Permafrost rework: Your Death Strike now grants you an absorb shield equivalent to 10% of your max hp.
2- Unholy (PvP)
2.1- Necrotic Wounds PvP Talent Removed.
2.2- New PvP Talent Necrotic Coil: Your Death Coil now becomes Necrotic Coil, which applies a stacking healing debuff on the enemy target absorbing 10% of all healing received for the next 15 seconds per stack. This effect can stack up to 3 times, stacking the effect does not refresh the duration.
2.2- Necromancer’s Bargain PvP Talent Removed.
2.3- New PvP Talent Might of the Necromancer: Apocalypse’s cooldown is reduced to 45 seconds and Apocalypse now deals 30% increased damage for every wound on your target, up to 6 wounds.
2.4- Raise Abomination PvP Talent Reworked: Your Dark Transformation additionally summons an Abomination to fight by your side.
2.5- Summon Gargoyle Talent now deals 60% increased damage.
2.6- Frenzied Monstrosity now deals 15% more damage and 15% increased attack speed (up from 12%, they nerfed it down to 12% at beta it was way stronger)
2.7- Superstrain Legendary is unnerfed.
2.8- The damage of Death Coil is increased by 50%.
3- Unholy (PvE)
3.1- Damage of Death Coil increased by 10% (In addition to the PvP Buff). This does not apply to PvP situations.
3.2- Damage of Scourge Strike/Clawing Shadows increased by 5%. This does not apply to PvP situations.
3.3- Bursting Sores now deals 30% more damage.
3.4- Ebon Fever Reworked: Applying Outbreak grants you Unholy Power for 15 seconds, which increases the damage of Epidemic and Death Coil by 15% for the duration.
3.5- Death and Decay now additionally causes your Death Coil to hit all targets while standing in it.
3.6- Frenzied Monstrosity now deals 15% more damage and 15% increased attack speed (up from 12%, they nerfed it down to 12% at beta it was way stronger).
3.7- Superstrain Legendary is unnerfed.
4- Frost (PvE)
4.1- Obliterate damage increased by 25%. This does not apply to PvP situations (In addition to the 10% damage buff in PvP section).
4.2- Frost Strike damage increased by 25%. This does not apply to PvP situations (In addition to the 10% damage buff in PvP section).
4.3- Pillar of Frost duration increased to 15 seconds.
4.4- Koltira’s Favor Legendary now increases Obliterate damage by 20% and provides 15% chance to refund runes.
4.5- Biting Cold Legendary now increases Remorseless Winter’s damage by 45% and increases its duration to 12 seconds.
4.6- Frostwyrm’s Fury damage increased by 10%.
4.7- Cold Heart Talent Reworked: Applying Chains of Ice now costs 30 Runic Power instead of 1 rune and Chains of Ice deals 300% of Attack Power frost damage to all enemies within 10 yards of your target.