Step 1: Ditched Countess Iseara. There was no one that I figured I would really want to give necromancy to that didn't already have it, other than the walking sacrifice, but that would be a 7 cost (6 for the countess + 1) snackrifice. The Slave Pen gives you lots of power, so I don't think her 3 power are all that amazing considering her unimpressive ability for 6. I'd rather play a legend at this point and I am really scared of playing legends. Also, it is Dark Elf tradition to call it a Walking Snackrifice. Now the magic number is 5 if I want to play my biggest unit.

Step 2: + 3 Chillwind with the new space

Step 3: - 1 Danse Macabre. Sure, it'd be awesome in certain situations, but my undead are not being cycled to the discard with enough consistency. Now we're at 50 cards.

The question is "Do I want to add Bladewind / Arkayne Vampire / Burn it Down?" I am going to say no to Har Ganeth because it isn't difficult to remove a unit with 1 HP permanently with Vile Sorceress, Seasoned Corsairs, or Offering to Hekarti. You have lots of murder cards. I'd say Danse Macabre is quite expensive to be so contextual, so I will replace it with Burn it Down.

Step 4: -2 Danse Macabre
+2 Burn it Down (I generally only put 2 devs in my battlefield when I'm running this card)

Things that I notice are missing: Ways to slow economy and knockout-punch power.

This deck did alright in our group, it played like a slow DE wait-and-see deck. Gaze of Nagash didn't go off once, but I can see it being amazing if it does. I'd like to get more reps before I cut it out because it is so devastating. Sorceress Covenant isn't doing much because once the opponent sees the hand destruction happening they just play all their cards.