Doomed Grass implements the famous "cursed earth" mechanic from mods such as Extra Utilities into the latest version of Minecraft.
To get started, you will need to kill wither skeletons until they drop a Doomed Fragment. The fragment can then be right-clicked onto a dirt-based block to convert it to doomed grass. Be careful, as the doom spreads to many nearby blocks. The block will then rapidly spawn mobs as long as the light level is low enough.
