Dark Realm

The Dark Realm is a Hardmode biome only accessed by using a Suspicious Mirror, which is a 100% drop from the Duplicate, a post-Plantera boss in Hardmode.

Appearance
The Dark Realm consists of a 180x200 block area made of the following materials: It also has trees made of Shadewood, and two oceans at either end with no bottoms and made of Shadow Lava instead of Water. There are also various Shadow Lava lakes throughout the Dark Realm and it's underground is riddled with caverns and tunnels.
 * Shadestone
 * Shadesand

Enemies

 * Shade Imp
 * Darkbat
 * Corrupt Warlord (If World Is Corrupt)
 * Crimson Destroyer (If World Is Crimson)
 * Shade Demon
 * Shade Archer
 * Shade Behemoth (Minibosss)
 * Ultimate Duplicate (Boss)

Drops

 * Shadite Ore (From all enemies)
 * Dark Fur (From Shade Imp and Darkbat)
 * Shadite Bars (From Shade Imp, Shade Demon, Shade Archer and Shade Behemoth)
 * Nightbringer (From Corrupt Warlord)
 * Crimblade (From Crimson Destroyer)
 * Shadecutter (From Shade Behemoth)
 * Evil Repeater (From Shade Behemoth)
 * Murderous Staff (From Ultimate Duplicate)
 * Cloner (From Ultimate Duplicate)
 * Cyber Engine (From Ultimate Duplicate)