How do you spawn an Eater of Worlds in an Artificial Environment?
I'd like to build an Eater of Worlds arena but I'm confused regarding what his summon requirements are.
I see some arenas built entirely of wood. The wiki vaguely references corrupted dirt (how much?) and ebonstone (200+).
The Eater of Worlds must be spawned in a Corrupted environment. There are certain requirements of a number of Ebonstone blocks for an area to be considered Corrupted. You need 200+. When you're in a Corrupted environment, the music and background will change. By watching/listening for that, you can know whether you can spawn the Eater of Worlds.