Love me some theorycrafting.

Ability Soul Reaper, after 5 seconds if target is below 35% hp - BOOM.
Read it can be dispelled. Two things, the glyph that makes diseases undispellable but reduces damage by 30% - work on this?
Place on then place diseases, or mix in with them, causing dispelling to not be worth it.

In the hectic form that is arena's. You've got 5 seconds after placement. In those 5 seconds popping defensive cooldowns so no loss of control of character using Antimagic zone, possibly using 2 would be safe - preventing a large amount of CC.
In total you get 3 globals, possibly 4 with all the haste that DK's have in that 5 second window to drop a target by 65%. 100% is tough but 65%..? that's seems totally doable no?
Weave in a necrotic strike to ensure low heals.

I keep hearing DK's have issues dropping targets but they seem more than able to become unhindered for a good 10 seconds and not be locked down, this seems like a great recipe to close that gap.

Tell me where this fails. I'm really tempted to level up my dk/paladin combo as well - the druid/sham combo is good but they are both oh so tempting.