The Idea:
Add a new resource for Unholy that rapidly is siphoned from enemies and consumed through different abilities. Think of it like the rapid movement of Energy, but it doesnt fill on its own or drain. (could be a modified runic power or a new thing, for this example, im gonna use Runic Power (RP) to explain)
Also please note that cooldowns/damage/healing/% values aren't thought out for balance, so take those with a grain of salt.
Unholy: Melee DPS
A master of death and decay, spreading infection and controlling undead minions to do bidding.
Maximum Runic Power raised to 500. Auto Attacks generate 10 Runic Power. Raise Dead and Army of the Dead remain the same. Retain Death Strike and other baseline Death Knight abilities. Dark Transformation also doubles the runic power generated from your ghouls attacks (10). Haste increases tickrate of all abilities, causes faster RP drain and faster spending. All abilities deal damage and drain RP every 0.5 sec.
Siphoners/Generators:
Scourge Strike: An unholy strike that deals 2750 Physical damage and 2100 Shadow damage. Costs 1 Rune. Siphons 50 Runic Power.
Outbreak: Inflicts the target and 1 nearby enemy with a Virulent Plague. Deals 10000 Shadow damage over 12 sec. Costs 1 Rune. Siphons 5 Runic Power each time it deals damage. 30% chance to erupt, dealing 2500 split AoE damage and siphons 3 Runic Power per enemy hit. 30 yard range.
Defile: Defile the targeted ground, dealing 8000 Shadow damage to all enemies over 15 seconds. Each time defile hits an enemy, it grows larger and deals 5% more damage (No cap). While in Defile, your Outbreak will hit 5 targets and Scourge Strike will hit all targets (No extra RP). Costs 1 Rune. Siphons 15 Runic Power each time it deals damage. 30 second cooldown. 30 yard range
Undead Minions: Passive. All unholy minions generate 5 runic power each time they hit an enemy.
Soul Reaper: Rip an enemies soul from their body, dealing 11000 Shadow damage over 8 seconds. Generates 2 runes immediately and 50 Runic Power over its duration. 45 second cooldown. Melee Range.
Spenders:
Unholy Blight: Channel a storm of unholy necrotic energy, dealing 8000 Shadow damage every second to all nearby enemies. Drains 50 Runic Power per second until drained. 45 second SHARED Cooldown. Channeled. (Shared CD with Necrotic Explusion)
Note: This would encourage a strong setup with other builders, summoning more minions, spreading dots, etc to feed you Runic Power to maintain this ability as long as possible.
Necrotic Expulsion: Channel a force of unholy energy into the target, dealing 15000 damage per second while maintaining the channel. Drains 40 Runic Power per second until drained. 45 second SHARED Cooldown. Channeled. Castable while moving. 30 yard range. (Shared CD with Unholy Blight)
Note: This would encourage a strong setup with other builders, summoning more minions, spreading dots, etc to feed you Runic Power to maintain this ability as long as possible.
Apocalypse: Bring doom upon the enemy, dealing 17500 Shadow Damage. Drains 300 Runic Power. 30 Second Cooldown.
Death Coil: Fires a blast of unholy energy at the target, causing 5500 Shadow damage to the enemy. Reduces the cooldown on Army of the Dead by 3 seconds and Dark Transformation by 1 sec. Drains 100 Runic Power. 30 yd range.
Cooldowns:
Army of the Dead: Same as live. Each ghoul attack generates 5 runic power.
Note: The added RP generation would add some fun factor to this ability.
Summon Gargoyle: Summons a Gargoyle into the area to attack the target for 30 seconds. Each time the Gargoyle attacks, you gain 20 Runic Power. 2 Minute Cooldown.
Unholy Frenzy: Incites you and your ghouls into an killing frenzy, increasing Haste by 20% for 12 seconds. 3 Minute Cooldown.
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As I run out of time to work on this for now, I ask that you guys leave your comments and thoughts, it was fun to put together. Again, please take numbers with a grain of salt, not thinking much about numbers balance while making thing.
In my eyes this makes for a fun spec that has a very high skill cap, something the game sorely needs more of right now imo.