The following post was written by our Unholy Death Knight guide writer Bicepspump. You can catch him on Twitch and follow him on YouTube.
The Unholy Death Knight has received a significant rework in Midnight, unlike anything we’ve seen since the Legion expansion.
The 
Festering Wounds that were introduced in Legion are now gone, replaced with a minion-summoning gameplay loop at its core (still revolving around 
Festering Strike and 
Scourge Strike).
More emphasis has been placed on our Disease gameplay with both the new Single-Target exclusive 
Dread Plague DoT as well as multiple new talents.
Our AoE is now decoupled from 
Death and Decay and we instead passively cleave via standard Scourge Strikes. Finally, we have a new core rotational ability called 
Putrefy which we use to sacrifice the minions we summon.
How the New Rotation Feels Compared to The War Within
The core gameplay in Midnight does feel similar to The War Within in many ways.
- We use Festering Strike to apply stacks, now on ourselves instead of on the target.
- We use Scourge Strike to spend these stacks, now summoning minions instead of bursting Wounds.
- We spend our Runic Power on
Death Coil in Single Target and 
Epidemic in AoE and we keep up our diseases with 
Outbreak. All of this very much like we have done for the last couple of expansions.
Putrefy: The New Ability That Defines Unholy’s Rotation
One of the core differences comes from the introduction of the new Putrefy ability. Pressing it makes our “oldest” ghoul deal damage to our current target and then explode for a nice AoE.
It comes with a single charge and a 30-seconds cooldown by default, which can be increased to two charges as well as a Cooldown reduction on 
Sudden Doom consumption via talents. Blizzard indicates that the spell should be an important part of our rotation due to the significant number of talents that interact with it:
Unholy Devotion causes up to two other ghouls to go into a frenzy, dealing 100% more damage for 3 seconds – Rewards tracking the number of ghouls you have and ideally their remaining duration, to ensure that you get the maximum benefit.
Unholy Aura provides Haste whenever you cast Putrefy – effectively creates a maintenance buff where you should cast Putrefy at least every 15 seconds.
Blightburst makes the explosion effect of Putrefy extend the duration of your plagues by 4 seconds and deals 100% of the damage the diseases would do in that duration instantly – nice synergy with our plagues and another source of plague duration extension.
Reanimation reanimates the ghoul you Putrefy as a Magus of the Dead and putrefies an additional ghoul during 
Dark Transformation – major source of Magus summoning that is further amped up during your Cooldown windows.
Putrid Echoes gives you an additional charge of Putrefy and increases its damage by 20% – provides some nice flexibility with the additional charge and enables you to both use the ability more efficiently, as well as spending the charges in a more burst-like manner. For example, with Reanimation you can summon 4 Magus of the Dead during your Dark Transformation for some nice AoE burst.
Forbidden Knowledge 3 increases the duration of 
Forbidden Knowledge 1 when you Putrefy.
All these interactions make Putrefy an important spell to cast that has a big impact on your damage. Blizzard has iterated heavily on the ability and it now feels pretty good to press. The main drawback is that you want to cast it quickly on pull, sacrificing a ghoul right at the start of its life.
One option is for the explosion to happen at the end of the ghoul’s life, but then you both remove some skill expression as well as the direct damage feedback from pressing the button (and delaying any Magus summons).
I cannot help to compare the ability to Frost’s Empower Rune Weapon which feels great to use, is off the GCD and has no cost, leaving Putrefy behind in the dust in terms of button feel.
Dread Plague and the New Disease Gameplay Rotation
Our Disease gameplay has also changed in Midnight. The War Within has some Disease interaction, mainly through the San’layn Hero Talents and 
Infliction of Sorrow.
Midnight introduces the Dread Plague Disease, a pure Single-Target (can only be up at one target at a time) which is also our new source of Sudden Doom procs.
You can pick up 
Rapid Variant to both get free spreads in AoE when your target dies (something you otherwise need to manually reapply with Outbreak) as well as an avalanche-like effect akin to Warlocks’ old 
Soul Flame ability.
We also get a default extension of our DoTs with Death Coil and Epidemic and spreading with Scourge Strike. This helps maintain and spread our DoTs while creating strong synergy with San’layn as longer DoT durations directly scale up the Infliction of Sorrow damage.
You get this interesting interaction where you ramp up your DoT duration during Cooldowns, gaining a ton of damage with Infliction of Sorrow. With sufficient Haste, you can then carry the duration into your next Cooldown window to burst even higher. You reach a steady state at some point based on your Haste but the gameplay does remind me of old Necrotic Plague which is really cool.
For Rider of the Apocalypse, the disease extension only really helps us avoid pressing Outbreak too much, which is okay but also quite a shallow interaction.
I would personally love to see a bit more active gameplay in the Disease department, it is generally quite passive still. One idea could be to change how Scourge Strike interacts with Diseases. It currently deals extra damage based on the next few ticks of your Diseases.
It could instead deal damage based off the total Disease damage you dealt on the target in the last few seconds (including stuff like Infliction of Sorrow). You could then play around prioritizing Scourge Strike after you have dealt a lot of Disease damage!
Goodby Death and decay: Unholy’s New AoE Style
Our AoE gameplay does change quite drastically in Midnight through the removal of Death and Decay as a cleave enabler. Instead, we now passively gain Scourge Strike cleave through the new 
Clawing Shadows talent.
Every time you hit Scourge Strike, you get a 12 seconds stacking buff with each stack making your Scourge Strike hit one additional target. This caps out at 4 stacks (5 total enemies hit).
It is great that we remove the need to stand in our Death and Decay, but it’s not ideal to have a maintenance buff that both ramps up and presents an awkward window to extend between packs.
More Range, Less Downtime is a Welcome Surprise for Death Knights
Our range effectiveness has also been impacted in Midnight. In The War Within we are pretty tied to the boss due to several factors. Without Clawing Shadows, two out of three of our core rotation buttons are Melee. Furthermore, Sudden Doom procs off auto attacks and Unholy Aura requires close proximity to the target. Most of this changes in Midnight.
Scourge Strike is 30 yards by default and Unholy Aura no longer has an AoE aura element. Sudden Doom procs off Dread Plague removing the need for melee auto (this does hurt our Haste scaling as Dread Plague tick rate is independent from our Haste).
Summing this up, we only really need to be in range to press Festering Strike ever so often. In the gaps in between, we can freely move around at range while losing minimal damage and the loss of uptime on pets as they run to the boss when summoned. This is a really positive change as the more versatility you have at range, the less impacted you are from forced downtime and mechanics.
New Talents That Supercharge Your Cooldowns
We’ve received three new extra talents in Midnight that you (optionally) talent into as you level up. Forbidden Knowledge 1 provides a 15-second buff when you cast 
Graveyard that transforms your Death Coil into Necrotic Coil and Epidemic into Graveyard. These new spells deal much more damage, cost less Runic Power (20 instead of 30), and have a 1-second GCD compared to the usual 1.5 seconds. They make your cooldown window super fast-paced as you can send out significantly more abilities than usual, both amping up minions like 
Summon Gargoyle as well as significantly extending our DoTs.
The other two talents simply empower Forbidden Knowledge, giving you Runic Power and ghoul summons as well as an extension of the buff with Scourge Strike ghoul summons / Putrefy usage. 
Necrotic Coil also has an AoE aspect where it both cleaves to 3 targets total, but also deals damage in the path of the coils themselves.
Graveyard has a similar Quadratic Scaling component as Epidemic but in a slightly steeper sense. It deals about 50% of the Single-Target damage in AoE compared to Epidemic that does 40%. We will have a classic case of “use Graveyard at X targets over Necrotic Coil”.
Fewer Cooldowns and Cleaner Windows are a Major Quality-of-Life Win
Finally, our cooldown amount has been reduced significantly. Both 
Apocalypse and 
Unholy Assault have been removed. We still have Army of the Dead but both Summon Gargoyle and 
Raise Abomination are summoned via Army. Dark Transformation is off the GCD as well, only leaving a single on-GCD cooldown for Unholy. Given the historical large number of cooldowns, this is a nice improvement that will simplify our opener and cooldown window a lot.
Final Thoughts: A Promising But Imperfect Rework
In summary, Blizzard has done a large number of good changes that help improve our gameplay. We are more versatile at range, have less ramp when we swap targets, aren’t tied to ground effects to deal AoE damage and do not have too many Cooldown buttons. It is also clear that Blizzard wants to focus more on minions and Diseases, making them a more integral part of our core rotation. I think the idea is very much there but the execution can do some work.
Spells like Putrefy feel somewhat awkward to press and lack a satisfying feedback loop. The Disease gameplay looks promising with San’layn but I would want a bit more. If we could get some cool skill expressions from playing around with our Diseases I would be very happy. I must say that I am overall pleased but I am also keen to see more development to get some more depth and skill expression in the spec.
