A single, infinite, flat plane of corrupted bedrock.
Dead Void is entered through the Corruption Level 3 endgame's Day 7 gate. It is a single, infinite, flat plane of corrupted bedrock (Y 0-1).
The Integrion Altar stands here, generated automatically the first time the player enters. This is where the mod's endgame leads: placing the Integrion Core on the altar summons the Integrion Bossfight.