Some where in essentials config.yml you disable withers from spawning by making it false, or get this plugin: http://dev.bukkit.org/bukkit-plugins/wither/
mobs: block-creeper-explosions: false block-creeper-block-damage: true block-wither-explosions: false block-wither-block-damage: true block-wither-skull-explosions: true block-wither-skull-block-damage: true block-enderdragon-block-damage: false block-enderdragon-portal-creation: false If prison has world guard they can just set the red to false in the prison world. This is the config for world guard, well part of it.
Then why did merks add a plugin that allows obsidian to be broken with tnt so you can grief factions?
I didn't know you can move anything the portal..... I only thought certain things could or couldn't...
So you can raid factions in the "Free" world not the prison world. If you type /gc or /lag you can see that there's 3 worlds, There's Free world, Nether, and the Prison world.
Greifing spawn is illegal on all servers. Greifing players land/islands however depends on the server involved.