The Hallow



The Hallow is an end-game surface biome. It has an easily recognizable cyan-colored grass, multicolored trees, and a huge rainbow in the background. It is the only biome where you'll find Unicorns, Pixies and Gastropods. The Underground Hallow biome can be found directly under a naturally-generated Hallow biome.

Hallow does not exist in a newly-generated world. It only appears when entering hardmode, which is done by defeating the Wall of Flesh. Then, one Hallow biome along with a large Underground Hallow biome are generated. The Hallow can also be artificially created by planting Hallowed Seeds in dirt, using Holy Water, or placing Pearlstone and Pearlsand blocks.

The Hallow is the only environment through which the Corruption can't spread at all (the opposite also seems to be true). Consequently, its role is very important in hardmode, where the corruption becomes nearly unstoppable. The Dryad will tell the player the percentage of Hallow and Corruption in the world. (Neither the Hallow nor the Corruption can spread through Hell, and the Hallow cannot spread through the Jungle.)

Although activating hardmode requires the player to have good equipment, the Hallow is a challenging biome, especially at night, since it is home to powerful mobs. Do not be fooled by the cute and childish scenery.

Hardmode
As soon as Wall of Flesh is defeated, a section of Hallow spawns. This stripe goes from the Underworld to the surface, converting stone, sand and grass in its path into pearlstone, pearlsand and hallowed grass, respectively. This does include floating islands that happen to be in the path of this stripe. Sometimes The Hallow's stripe can intersect with Corruption chasms making easier access.

Hallow spreads in a manner very similar to corruption:
 * Hallowed grass can spread to dirt or grass blocks in the Surface Layer with at least one side exposed to air.
 * Stone can be converted to pearlstone.
 * Sand can be converted to pearlsand.
 * Ice can be converted to Pink Ice.
 * 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 hallow spreads:
 * Hallow can spread through its vines (but can not "go up" through regular vines).
 * 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.
 * Hallow cannot convert mud or jungle grass. This means the Hallow can be completely superseded by the Jungle causing no blocks to become Hallow.

Pre-hardmode
Hallow does not normally exist before the world enters hardmode, but can be created with Hallowed Seeds or Holy Water imported from another world. If it is created, it will only spread the same way as pre-hardmode Corruption: 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 mobs will not appear, since they were only designed for hardmode.

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 mobs are the same (except the Light Mummy), 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.