Dark Sethbling is one of four "Coin" classes which you can get with no coins at all. Dark SethBling is received when you find all 10 SethBling heads scattered in the spawn area.
Equipment and Abilities EditDark Redstone Sword: Sharpness II, Knockback II
Whenever you pick up an item, you get Strength II for the rest of the current life
Location of the Heads Edit
#1: At the spawn to the left of the SethBling maps section
#2: At the spawn to the right of the SethBling maps section
#3: Inside the stomach of the Dragon in "SethBling's Hut"
#4: On a lapis arm of the Dragon near the mouth
#5: Inside the Pile of Bodies waiting room on next to the class signs