Find the gravedigger guy on evil side, say bring to him. He hands you a shovel, tells you to go to Field of Scale or Loping plains. I went to loping plains, near the hills of shade zone line theres a bunch of disturbed earth mob types around. Target one, click the shovel. You'll get a random undead, the one your looking for is a tattood zombie. kill it, loot the skin, hand skin and shovel back to gravedigger. Rinse n repeat for 5 days. its only a 17 hour lockout between tasks, but I did it every night before I went to sleep, took like 10 - 20 minutes each.