The problem with Unholy DK Damage falls squarely on poor overall design of the tier set bonuses in addition to the lack synergy that the legendary powers provide.
The 2 piece set only triggers when 5 Festering Wounds have been burst by either Scourge Strikes or Clawing Shadows
What Unholy Signature Ability is missing that utilizes the bursting of festering wounds as well?
In terms of Soul Reaper and the summoned Ghoul just aren’t providing the passive damage increase that is required versus other classes. It states the Ghoul is summoned for 15 seconds but a key issue Unholy had previously and should be checked is in relation to the duration of the ghoul vs the duration which the ghoul is actively doing damage.
The 4 piece Soul Reaper secondary effect only triggers when the target is under 35% so has no value and does absolutely nothing above that point. The addition of the percentage increase to minion damage is clearly a straight up attempt to provide some passive band-aid. However, the passive increase isn’t providing anywhere near the passive increase required to make the set design competitive vs others.
When you take a look at the Frost DK Set Design there is clear design synergies that are working extremely well in combination with certain abilities, talents and even legendary powers. The two piece works to provide a significant increase to Killing Machine during Remorseless Winter windows passively and has no functional limitations or required triggers conditions.
Frosts 4 piece design utilizes Killing Machine and the simple fact that they have more of them due to the 2 piece effects. Then having a Glacial Advance fire off anytime they utilize Killing Machine provides free consistent damage increase that works regardless of health percentages.
Frost also gains additional passive synergies with the overall set design with things like Might of the Frozen Wastes in terms of 2-Handed Frost when combined with the legendary power Koltira’s Favor. Dual Wield has similar synergies with Breath of Sindragosa and Rage of the Frozen Champion with the option to use Biting Cold instead if breath can’t be maintained.
They need to consider the overall aspect of design synergy for Unholy because right now it is a discombobulated collage that just isn’t working.