The Hallow



The Hallow is a Hardmode surface biome. It is characterized by pastel-colored fairytale graphics, with cyan-colored grass, multicolored trees, and a large rainbow in the background, as well as similarly whimsical-looking (though dangerous) enemies. The Underground Hallow biome can be found directly beneath a naturally-generated Hallow biome.

The Hallow does not exist in newly-generated worlds. It is generated along with a large Underground Hallow biome when the Wall of Flesh is defeated for the first time and the world converts to Hardmode. Once generated, Hallow spreads in a manner similar to Corruption or Crimson. Pearlstone, Pearlsand, and dirt blocks growing Hallowed grass will spread Hallow to neighboring blocks, causing Hallow enemies to spawn over ever-larger areas. Hallow can also be seeded in new areas via Hallowed Seeds, Holy Water, or Blue Solution with the Clentaminator.

The Hallow is the only environment through which the Corruption and Crimson cannot spread at all, apart from the initial Hardmode conversion that takes place when the Wall of Flesh is defeated. Hallow also cannot spread through mud biomes like Jungles or Mushroom Biomes (unlike Corruption/Crimson, which can convert Mud into Dirt).

The Dryad can tell the player the percentage of Hallow and Corruption/Crimson in the world.

Spreading
Much like the Crimson/Corruption, the Hallow also spreads. It may spread to dirt, sand, stone, and ice. The Hallow however, does not spread nearly as quickly as the Corruption or Crimson does.

Hardmode
As soon as Wall of Flesh is defeated, a section of the Hallow spawns. This strip goes from the Underworld to the surface, converting Stone, Sand and Grass in its path into Pearlstone, Pearlsand and Hallowed grass, respectively. The Hallow's stripe can intersect with the Corruption's or Crimson's chasms as well as Floating Islands.

Hallow spreads in a manner very similar to Corruption and Crimson:
 * Hallowed grass can spread to Dirt Blocks or grass in the Surface Layer with at least one side exposed to air.
 * Stone Blocks can be converted to Pearlstone Blocks.
 * Sand Blocks can be converted to Pearlsand Blocks.
 * Ice Blocks can be converted to Pink Ice Blocks.
 * Pearlstone and pearlsand can spread through any depth, not just the Surface Layer.
 * Blocks that are up to three squares away from an existing hallowed block can be converted, even if unhallowable blocks are in the way.

There are also a few differences in the way that the Hallow spreads:
 * The Hallow can spread through its vines (but can not "go up" through regular vines).
 * The Hallow does not uproot sunflowers, but can still spread beneath them.
 * Pearlstone does not seem to create hallowed grass as fast as ebonstone creates corrupt grass.
 * The Hallow cannot convert mud or jungle grass.

Killing Plantera slows the spread of Corruption/Crimson/Hallow to 1/3 of its original speed.

Pre-hardmode
Hallow does not normally exist before the world enters Hardmode, but can be created with Hallowed Seeds, Holy Water, or the Blue Solution (for use with the Clentaminator) imported from another world. If it is created, it will only spread the same way as pre-hardmode Corruption/crimson: slowly, on the surface, and only through dirt and grass. This means you can safely use other hallowed blocks without creating a biome and converting regular blocks in pre-Hardmode worlds. It still prevents the Corruption from spreading. Furthermore, Hallow-specific enemies will not appear, since they were only designed for Hardmode.

Trivia

 * The word 'hallow' means "to make holy", meaning that the name Hallow likely means 'holy land.'

Hallowed Desert


When the Hallow spreads through desert, it becomes Hallowed Desert. It is very similar to the Hallow: the music theme is the same, the enemies are the same (except for the Light Mummy and Crystal Thresher), and the background is slightly different.

The sand is replaced by pearlsand. Although their color is different, cacti still drop cactus when cut, and waterleaves are also able to grow.

History
Das Heiligtum La Purification 神圣之地