Hearthpwn

I used the deck below. It may not be completely refined, but I have a 65% win rate on 17 games at D5-D1. 

General Idea is to keep them busy with Curses and Sludges. Curses make them use mana and slow down their game, sludges can be used to clear the board of push damage. Forge of Wills plus 7/7's make for good board presence that they will have to answer.

You can heal with Pop'gar the Putrid or Dar'Khan + Infantry Reanimator.

Late game, you have multiple win conditions. You can out value them with Sargeras, the Destroyed, Lord Jaraxxus, or kill them with curses. 

If you face off against a Plague Death Knight, my advice would be to get Sargeras and do as much damage as possible, then use Tony to copy their deck and get rid of the plagues in your deck. Haven't had to do this, but it is the idea behind it.

### Curse/Sludge Warlock
# Class: Warlock
# Format: Standard
# Year of the Wolf
#
# 2x (1) Miracle Salesman
# 2x (1) Tram Mechanic
# 2x (2) Disposal Assistant
# 2x (3) Dragged Below
# 2x (3) Forge of Wills
# 1x (3) Furnace Fuel
# 1x (3) Prince Renathal
# 2x (3) Sira'kess Cultist
# 2x (3) Sludge on Wheels
# 2x (3) Trogg Gemtosser
# 2x (3) Trolley Problem
# 2x (4) Imposing Anubisath
# 1x (4) Pop'gar the Putrid
# 2x (4) Waste Remover
# 2x (5) Infantry Reanimator
# 1x (5) Symphony of Sins
# 1x (5) Taelan Fordring
# 1x (5) Za'qul
# 2x (6) Abyssal Wave
# 2x (6) Chaos Creation
# 1x (7) Dar'Khan Drathir
# 1x (7) Prison of Yogg-Saron
# 1x (7) Tony, King of Piracy
# 1x (8) Lord Jaraxxus
# 1x (9) Sargeras, the Destroyer
# 1x (9) Yogg-Saron, Unleashed
#
AAECAdX8BQyoigSFoATmvQSX7wTOkgX5xgXN0AX++AWm+wWplQaAngb3owYO/rQE3L0E4r0EjpIF1/oF7f0FhY4GlZcGlpcGl5cGmJcGoqAGq6AGpqgGAAA=
#
# To use this deck, copy it to your clipboard and create a new deck in Hearthstone