Cursed Earth (Extra Utilities 2)

Cursed Earth is a block added by Extra Utilities 2. It is created by using a Drop of Evil on Dirt or Grass. Only the block the Drop of Evil was used on can be harvested with Silk Touch

Hostile mobs spawn at a vastly increased rate on it and spawn with a large bonus to their attack damage and movement speed, and also appear black. When initially created, it quickly spreads through Dirt and Grass in a large area, then continue to spread to nearby Dirt. Cursed Earth can not cross gaps while initially spreading, but can go up and down 1 block.

Setting Cursed Earth on fire causes the fire to quickly spread to the whole patch, turning it back to Dirt as the fire finishes burning.