Hearthpwn

I climbed from 10k legend to triple digits with this version in 1 day.

Mulligan Tips:

General Mulligan: Scarab Keychain, Mining Casualties, Gold Panner

Vs Warrior : Runes of Darkness, Down with the Ship Helya, Dirty Rat

Vs Aggro: Threads of Despair, Crop Rotation

Vs Other DKs you wanna maximize your card draw, spend corpses fast and drop Climactic Necrotic Explosion and win.

Pro Tips:

Vs Warlock you wanna save your Plague cards till they use Wheel of DEATH!!!, 2xDown with the Ship is 14 damage you can basically finish them off by pressure.
Vs Druids your time to Dirty Rat is after they draw with Summer Flowerchild so you can hit their Owlonius.
Vs Warrior you wanna shutoff Brann and they will concede if you fail to shuffle some duplicate plagues by the turn before they can play Brann you take your chances with Dirty Rat.

Board Clear Combinations:

Threads of Despair+Crop Rotation is a good board clear.
Sickly Grimewalker+ Crop Rotation is another good board clear.
Sickly Grimewalker+ Hero power + Threads of Despair is the perfect board clear.