I've been toying around with this idea in my head for new abilities and I really started to love this one in particular. If this thread is too redundant, I apologize. Here's the Idea:
The Deathknight's skills as a Necromancer have grown, allowing their minions to grow in power and gain new abilities based on specialization
Blood - Summon Vampiric Servant (replaces Summon Ghoul)
The Deathknight's ghoul is empowered with vampirisim allowing it to siphon off health from it's target and gift it to it's master. When the Deathknight uses Runetap, the Servant sacrifices a percentage of it's health to heal all party members within a 40 yards and places a blood shield on them. This shield is affected by the Deathknight's Mastery rating.
Frost - Summon Ice Wrath (replaces Summon Ghoul)
The Deathknight's ghoul grows ice shards allowing each hit to also deal frost damage to it's target. Each strike also deals a stacking debuff called Ice shards. When Ice shards reaches 10 stacks, it shatters the target dealing Frost damage to the target and spraying razor sharp shards to all enemies with in 15 yards.
Unholy - The Dark Half (new ability) 3 min cooldown
The Death Knight splits the necromatic energy coursing through it's ghoul, forcing it to wretch it's skeleton out. The skeleton then takes the form of a Skeletal Mage for 30 secs and cast shadow bolts at it's target. The ghouls damage is reduced by 25% when used.
The skeletal mage is also affected by Dark transformation. When it transforms, it's shadow bolt becomes a shadow bolt volley.
That's it. Of course all other ideas are welcome. I would love to hear them.