The Apparition

"Making the world frightful..."

The Apparition is a Hardmode hazardous surface biome presenting a "haunted" theme. It has dead grass, dead trees, and white water. Here, Zombies have an increased spawn rate at night, and sometimes spawn at the day, where they can survive in the biome, but not anywhere else in the day.

It generates as a biome that spawns where the Wraith Lord has died. If the Wraith Lord was killed underground, the biome will generate on the surface and not underground.

The Dryad can tell the player the percent of Crimson, Corruption, Cyber, Hallow, and if there is any, The Apparition.

Spreading
"The land around you looks scary..."

The Apparition isn't generated initially in a world, it is only generated by defeating the Wraith Lord. After that, the surrounding land becomes The Apparition which grows at the rate of the other hazardous biomes in Hardmode, with the message, "The land around you looks scary...", which may come as a surprise to unsuspecting players, as it can also scare NPCs out of their house.

Additionally, the Apparition may also completely disappear from the world after defeating The Grim Reaper. After defeating it, all the Apparition in the world will become the biome it used to be. After that, the Apparition can also return after the Grim Reaper if you beat the Wraith Lord again, in which a new spot of Apparition spawns, or if you get the Reaper's Scythe which if you get the Death Essence, a drop from both bosses, you can turn certain blocks into Apparition blocks.