Guide:Wall of Flesh strategies

The Wall of Flesh (or WoF) is a huge wall of flesh. It has two eyes, which shoot lasers at you, and one mouth. It also has many small creatures near it called The Hungry. They are connected to the WoF with long tendrils, which break once the Hungry take enough damage, releasing them to fly toward you.

Once you have beaten the Wall of Flesh, you will receive an ominous message and your world will enter Hardmode.

Summoning The Wall of Flesh
To summon the Wall of Flesh, go to The Underworld, kill a Voodoo Demon carrying a Guide Voodoo Doll and collect it. Drop it into a lava pool in The Underworld to awaken the WoF (Wall of Flesh). A word of warning, the WoF can accidentally be summoned by killing a voodoo demon over lava and allowing the voodoo doll to fall into the lava. This will not work if the Guide is not currently alive, you still have the Horrified debuff from a previous fight or you throw it in a lava pool that is not in The Underworld. If you are using the pocket edition, simply consume it to summon the Wall of Flesh.

Terrain preparation
There are multiple approaches you can take for fighting this boss, each having several strategic implications.

Full Preparation
You will benefit from preparing the area ahead when fighting the Wall of Flesh more than with any previous boss. An optimal arena is a perfectly flat land bridge of length at least 500 blocks, although you can need as much as 2000 with poor equipment. Lighting is relatively optional as the area will be well-lit from lava and other effects. Note that the height of the bridge does not especially matter, as the Wall of Flesh will move its eyes and mouth to the appropriate height for combat on its own.

Headroom to maneuver above the bridge may be useful, and additional wooden platforms can provide further mobility options, especially types for melee users. Also, if you have access to the Frostspark Boots, making the arena out of ice will allow much faster speeds to outrun the Wall.

It also helps tremendously for players who tend to get hit often(or just as a precaution) to station the nurse about halfway through the arena to heal yourself, even if you have the potion sickness debuff. If the house is small enough, you can jump over it easily. The nurse dying is unlikely, especially if she is in her house and the doors are closed; even without her in her house, the wall should pass over her without serious damage.

If you can jump boulders, then you should set up a few at the beginning of the run and wire them to a pressure plate in the course, so you can step on the pressure plate, and the Wall of Flesh gets hit by a few boulders, but them hitting you can seriously affect the battle, because they do a lot of damage. Explosives (or just thrown Dynamite) can be used in a similar manner for even greater damage. You can also set up heart statues connected to pressure plates to heal up.

Partial Preparation
If a full arena isn't desired, or you're not interested in wasting time on a world you don't intend to keep, you can make less extensive preparations. Run your bridge over any lava pits, make sure there aren't any especially difficult jumps to make, and clear a path through any major outcroppings. You may want to extend your work to closer to 750 blocks, as the fight will drag on while you jump over obstacles.

Partial preparation favors ranged combat, as you won't be within melee range often. You also will need to keep a bigger distance to account for any slow climbing you'll need to do. If you have large flat segments, those would be good times to close to melee.

Gearing Up
While the Horrified debuff has the effect of instantly killing you when you use your Magic Mirror, it does so after you return to spawn, allowing you to recover your money and (on mediumcore) items instantly. Obviously, it's a last-ditch strategy, and one that serves no purpose for hardcore players.

Armor
Molten armor, especially considering you will have to use this once hardmode starts as well. Nevertheless Crimson, Shadow or even Meteor armor, Necro armor or Jungle armor are valid options.

Melee Weapons
A primary concern about melee in this fight is that you are constantly moving away from the boss. As it is impossible to back up while swinging a sword, weapons like the Night's Edge are forced to stay dangerously close to the boss and catch it on the backswing if they wish to damage it directly. This would be nearly impossible without full terrain preparations.
 * A melee weapon especially helps when fighting the numerous Hungries, as one swing can hit many at once. Balanced characters may wish to start with a melee weapon to clear out the little creatures before switching to range or magic to fight the boss. The Wall of Flesh has a low defense, so the player isn't limited to necessarily using the strongest weapon that they have available.
 * You can also use a Flail. Obviously, you should use the Sunfury, because it is the strongest of its tier pre-hardmode. This is a good choice because it will do multiple damage to the Wall of Flesh. Same applies to the Dark Lance. Getting either the Dark Lance or the Sunfury is recommended if the player intends to focus on melee.
 * While they are obviously weapons of considerable range, the Flamarang and Thorn Chakram are considered melee, thus they benefit from the damage bonus of the Molten Armor set. They can be used after the Hungries have been mostly dealt with, as they are a safe, reliable, and inexpensive way to whittle him down. If several players are available for the fight, equipping each with a Flamarang is an easy way to take this boss down with minimal risk of death, or running out of ammo.
 * Night's Edge or other high damaging swords are viable options for fighting the Hungries, and thus is a good way to start the fight, but probably shouldn't be relied on for completing the entire battle.

Ranged Weapons
The ranged approach is safer but slower for this fight. When choosing ranged weapons consider taking the Necro armor, as the set bonus will reduce the ammo consumed, and the lowered defense should be mitigated by the distance between you and the wall. If you are going to use ranged magic weapons consider using Jungle armor instead.
 * Spiky Balls are a good way to start the fight. If you are going to use ranged weapons throughout the entire fight these can help you kill some of the Hungries quickly and dealing some additional damage to the WoF.
 * Alternately you can use piecing or exploding ammunition, such as Meteor Shots, Hellfire Arrows or Jester's Arrows. Gun users will want to use a Phoenix Blaster, Minishark or possibly even a Star Cannon. Bow users are best off using a Molten Fury or Sharanga. With any choice, you will want to bring a significant amount of ammunition (about 1,500 to 2,000) to ensure you do not run out. Other bows and guns should be avoided, especially considering you will need to use this in hardmode as well.
 * Explosives, such as Grenades, may work as well, quickly clearing the Hungry. Even Bombs and Dynamites can be used. Although the timing may require some practicing it is not a great deal if the area is damaged, as you won't return to there till the fight is over. Perhaps the better option of explosives are Beenades. By the time you are prepared to fight the Wall of Flesh farming them from the Queen Bee should be trivial.
 * A Waterbolt, Ruby Staff, Diamond Staff or Demon Scythe can deal a hefty amount of damage to the boss, while also providing piercing to quickly clear the Hungry.
 * Flamelash and Magic Missile perform poorly in this fight. The rate of damage is abysmal when dealing with Hungries or the wall itself. They are good at hitting mobile enemies in a static environment, which is the exact opposite of the situation here.
 * Bee Gun high speed, enemy following, and bouncing(5 times) ability can be very powerful weapon for this fight.

Accessories
Without full arena preparations a Obsidian Shield is recommended to prevent being knocked into the lava or receiving damage from Hellstone. Furthermore Spectre Boots or Lightning Boots, and a Cloud in a Balloon will help you maneuver around easier, while also helping you evade the lasers shot by the WoF. Other good Accessories are the Feral Claws for melee users and Band of Regeneration for all users. In addition, a Lava Charm or Lava Waders can be useful as an alternative to Obsidian Skin Potion. If you have one and have either a bad aim or a relatively small amount of ammo, the Ammo Box should be activated before the fight, and it usually will last the whole fight and provide a chance not to consume ammo.

Reforging your accessories for more defense or damage will help with this fight. Reforging for movement speed will help later on in the battle, but Spectre Boots usually would outrun the Wall.

Potions

 * As always a sufficient amount of Healing Potions will greatly help you survive.
 * Ironskin Potions will give the much needed defense boost. Each point of defense is more valuable than the last; the effects of this potion will be quite noticeable to most players.
 * Regeneration Potion is another useful survivability boost.
 * Swiftness Potion This is extremely useful to keep outrunning the WoF, especially once it's low on health and moving far faster than normal.
 * Obsidian Skin Potion and Water Walking Potion are good if you have no full arena preparations or if you meet the end of your area.
 * Also using Gravitation Potion and Featherfall Potion will help you if you have no full arena preparations.
 * Magic users should also bring sufficient Mana Potions and consider using Magic Power Potions and Mana Regeneration Potions.
 * Shine Potions, Night Owl Potions and Hunter Potion can help as well, even through there is some light already.
 * A Bowl of Soup/Cooked Marshmallow/Pumpkin Pie will give you a small buff in most stats.
 * An Inferno Potion will help a lot, as it can quickly get rid of the hungry, and hit the WoF itself when you are in close range.

Threat Analysis

 * It has two large eyes. They shoot lasers at you, so it is good idea to be as far away from them as possible.
 * These share health. Defeat these to defeat the boss.
 * The eye lasers do not penetrate blocks, so a land bridge effectively eliminates half of the lasers.
 * There is also a mouth, which will deal heavy damage to you if you get too close.
 * This shares health with the eyes.
 * It has a slightly higher defense value, so you may favor attacking the eyes instead.
 * There are many small creatures in front of it called the Hungry, held to the wall by long tendrils.
 * If you kill them, they disconnect with one third health and will fly toward you.
 * These small creatures mostly block you from being able to attack the Wall until they are killed.
 * As you whittle down the Wall's health, the tendrils on any still-attached Hungry can reach out further, making it easier for them to reach you as well as interfere with ranged attacks.
 * The Wall's travel speed will increase as its health is diminished, allowing it to catch up faster/forcing the player to retreat quicker.
 * As the Wall loses health his lasers will start to shoot faster and faster so dodging can become tricky.
 * The Wall's mouth will spit leeches, which can damage you, but will also always drop a heart, making them useful to kill when you're low on health, but it is good to kill them almost immediately by aiming a ranged weapon at the mouth, as the leeches are one of the main sources of the Wall's damage.

Strategy
The Wall will steadily move toward you, so keep your distance and plan ahead. If you get behind the Wall, it will pull you in front of it. You will be a little bit disoriented and possibly heavily damaged, so staying in front of it is absolutely a top priority. On the other hand if you move too far away from the Wall it will also pull you back.

At the start of the fight you should focus on killing the Hungry, preferably using a melee weapon or piecing/exploding weapons. When the little creatures have been mostly eradicated, you can now focus on the eyes and mouth. Ranged players should, from about this point, take very little damage for the rest of the fight. Melee players, in contrast, may take hits from newly spawned Hungry and the occasional direct hit from the Wall, but will start to deal massive damage if they have a spear or flail.

After defeating the boss, the loot will be enclosed suspended in a box, so lava is not a problem. However your world will enter hardmode if it isn't in hardmode yet.

After
After defeating the Wall of Flesh you will have accesses to stronger weapons, Emblems and stronger armor making the fight a lot easier. Furthermore, if after killing the WoF you immediately summon him again (of course waiting for the Guide to respawn!) you can pick up the Hearts left behind from last fight. This can be a great source of income, as Guide Voodoo Dolls are relatively easy to obtain.