The Parallel

"The Gateway has opened"
The Parallel is a dark version of the world that can be accessed with the Gateway, which is dropped by the Eye of the Ultralord. Different versions of enemies, bosses, and biomes can be encountered there.

Notable differences in the biomes include:
 * Parallel Crimson- 
 * Darker and decaying. Entering the Underground Crimson without inserting the Crimson Key into the Gateway will result in a bloody Parallel Guardian killing the player
 * Enemies:
 * Rib
 * Floating, red ribcages with an eye on the sternum, will float around and fire beams of blood at the player from the eye.
 * Tapeworm
 * A long, white worm enemy which can be found in the Underground Parallel Crimson
 * Brain
 * A brain that is attached to a block by a spine. Will act like a Snatcher/Man Eater, reaching and swinging at the player in an attempt to do contact damage
 * Bloodbag
 * A floating, bloated corpse with blood leaking out of its eye sockets, mouth, and the various tears in its body. Will attempt to spray blood at the player
 * Veins
 * Veins and arteries which have become an amorphous, net-like creature. Will slither along the ground and attempt to come into contact with the player.
 * Parallel Dungeon