Guide:Surviving in the Hallow

Overview
Alright, let's say you just beat the Wall of Flesh. After some more exploring, you may find a strange, colourful section with rainbows, unicorns and pixies. Congratulations! This biome is called the Hallow. It was one of the two biomes generated after you killed the Wall of Flesh, the other one being your Underground Corruption/Crimson. The Hallow is a deceptively difficult biome, with the three mobs that spawn here being very dangerous. Therefore, to deal with these threats, it is advisable to have:
 * The Night's Edge/Breaker Blade (Both are good, but the Breaker Blade is high reach and high knockback, whereas the Night's Edge does more damage.)
 * Yoyos are quite a good weapon here. If you have an Amarok, (1/75 drop chance from any enemy in the Snow Biome) this is the perfect weapon for the Hallow, as this does the most damage of any Yoyo Pre-Mechanical Bosses and inflicts Frostburn. The Hel-Fire is similarly quite good and inflicts Fire damage.
 * Roughly 30 defense or more. This helps to negate some of the high damage that Pixies, Unicorns and Gastropods do. I recommend Molten Armor or Crimson Armor. In the latter's case, use Warding/Armored reforged Accessories. In the former's case, use some Warding/Armored and some Angry/Menacing.
 * Movement accessories, to dodge the fast-moving Unicorns, the erratic flying patterns of Pixies and the lasers shot by Gastropods.
 * A Molten Pickaxe/Reaver Shark (for digging through the Pearlstone found in the Hallow).
 * AT LEAST 18 hearts. 20 hearts is recommended, as the extra 40 health may be what saves you from the mobs in the Hallow.
 * Note: This is just a guideline. Please feel free to add anything that you deem necessary to survive.

Surviving
When you first venture into this colourful biome, you will probably notice a strange yellow thing that floats around in odd patterns. This is a PIXIE. As pretty as it looks, do not be deceived! It has high damage, high knockback resistance and moderately high health. This is the most common enemy in the surface Hallow.

If you see a unicorn (which does not need to be described as it is pretty much straight-forward looking) then BE CAREFUL!! This is the more dangerous of the two, having high damage, VERY high knockback resistance and high health. It has one attack: to charge into you at high speed. When you see this, just use a high knockback weapon OR the Amarok/Hel-Fire.

If you wish to stay at night (NOT recommended), then you will meet an (ugly) mob. It shoots lasers and is pink, but is mostly a ranged mob, unlike the other Hallow mobs. It is a slime, meaning that if you have killed King Slime in Expert Mode, Royal Gel makes you immune to them. (Hooray for Royal Gel!) I'd say this is a mob to be wary about. Its projectiles are fast-moving, but relatively easy to dodge with proper care.

If you are in Expert Mode, the Shield of Cthulu is a lifesaver, underground and above ground. Unicorns charging at you? Shield of Cthulu them! Chaos Elementals teleporting around you? Shield of Cthulu them! (When in the Post-Plantera dungeon, you may find youself with something called a Tabi. This is an upgraded version of the Shield of Cthulu, and can be crafted into something called Master Ninja Gear, far superior to the Shield of Cthulu. But it's Post-Plantera, so we won't worry about that.)

Enemies
The hallow has several types of enemies. These include:

(while raining)

At night:

In a Hallowed Desert:

In the Underground Hallow: Enchanted Sword

Resources you will find
The main resources you find in the Hallow are Pixie Dust, Crystal Shards, Light Shards, Souls of Light and Unicorn Horns. Most of these are necessary for game advancement (Pixie Dust and Crystal Shards are 100% necessary, for Greater Healing Potions, something that won't be eclipsed until Post-Moon Lord.) Light Shards are not necessary, but useful, as they can make the Dao of Pow, a strong flail. Unicorn Horns are very useful, because they make Holy Arrows (which are extremely strong against the Destroyer), the Rainbow Rod (Prismancer!) and Super Mana Potions, which makes Unicorn Horns almost prohibitively necessary for Mages. Souls of Light are necessary for game advancement, as they make both the Mechanical Eye and the Mechanical Skull (necessary to make) Light Discs are a very good boomerang weapon, and what is good about them is that they give off light AND they are stackable in 5. (Bananarangs are stackable in 10, and do more damage, but they are a rare drop from Clowns, which only spawn in Blood Moons. This makes them ridiculously hard to get.) Angel Wings are likely the first wings you will get, and the last thing you do with Souls of Light are to make the Dao of Pow (along with Light Shard, Dark Shard and 7 Souls of Night.)