Wall of Flesh

"...The master and core of the world..."

The Wall of Flesh is a boss that is spawnable in The Underworld. It is the final and generally considered to be the hardest boss in pre-Hardmode (although, it is not quite as difficult to defeat as the Dungeon Guardian enemy).

To defeat the Wall of Flesh, the player must attack either its eyes or its mouth. They all share the same life counter, so shooting at any of the three will deplete the boss' total health. Shooting at the eyes causes the most damage, as they have the lowest defense. Its other body parts are transparent to weapons, so attacking those will not deplete its health, such as the Wall itself.

Summoning
The Wall of Flesh is summoned when a Guide Voodoo Doll is dropped into lava in The Underworld while the Guide is alive (this must be done in The Underworld; lava in any other layer will not work). This kills the Guide and summons the boss. It can be done either by killing the Voodoo Demon that carries the Doll while it flies above a lava pool, or by picking up the dropped Doll and throwing it into the lava yourself. On the, you can simply tap it in your hotbar, or you can drag and drop it from your hotbar to the lava.

If the Guide is not alive when the Doll is destroyed, the Wall of Flesh will not spawn, and the Doll will be wasted. If you have already summoned the Wall of Flesh recently, make sure the Guide has respawned before attempting to summon the Wall again. On the and, one can use the housing menu to see which NPCs are still alive. On the, you can check the minimap to see if the guide is there or not.

The Wall of Flesh's sweep direction is determined by its spawn location. Spawning it anywhere left of the center of the world will cause it to sweep from left to right, while spawning it right of center will cause it to sweep right to left. Maximum fight space can be achieved by spawning it at the extreme right or left of the world, though these areas have fewer natural structures and may require additional lava survival gear or construction.

Summoning The Wall of Flesh too close to world border will not spawn him even if the Guide is alive. (Sometimes the guide does not show up on the map).

Attacks
The Wall of Flesh is very large, occupying the entire screen vertically. Once spawned, it steadily sweeps across the map in a single direction, forcing the player to constantly move away for the duration of the fight while contending with the Underworld's usual hazards. The Wall of Flesh moves faster as it gets more wounded, and, on Expert Mode, it can reach up to 40 mph (as compared to the Hermes Boots at only 30 mph) during its last few hundred health. It must be killed before it reaches the end of the map, otherwise it will despawn and all living players in The Underworld will die (with the unique death message " was Licked.").

Keep this behavior in mind when preparing an Arena, as the fight will take you many screens away (unless you are already using Hardmode gear). Any platform you build will need to be very long.

Additionally:
 * The Wall has small mouths called The Hungry, each attached by a long vein, which move towards and damage players. As the Wall of Flesh's main body takes damage, they deal more damage and become more resistant to attacks. When they've suffered enough damage, they detach and chase players. In Expert Mode, the Hungry respawn as long as the Wall is alive.
 * The Wall's eyes fire lasers. As its health decreases, the lasers increase in damage, speed, and frequency.
 * The Wall burps Leeches from its mouth that chase players. These will always drop Hearts when killed.

Immediately upon the Wall of Flesh's spawning, the player is afflicted with the Horrified debuff, which prevents fleeing from the battle. Players that attempt to leave the Underworld or get behind the Wall of Flesh are grabbed by The Tongue and pulled directly into the Wall of Flesh's mouth, inflicting serious damage. If the player teleports beyond the reach of the tongue by using a Magic Mirror, Recall Potion or other means of quick transport, the debuff instead kills them immediately, returning the message " tried to escape." This can also happen after dying, if you try to return to the boss.

Aftermath
When the Wall of Flesh is killed, it leaves its drops in a floating, fully enclosed box of Demonite Bricks if your world was generated with The Corruption, or Crimtane Bricks if your world was generated with the Crimson to prevent its drops from falling into lava. One of the drops is always the Pwnhammer, which becomes an essential tool that helps players transfer into Hardmode.

After defeating the Wall of Flesh for the first time, a mini box on the bottom left corner will show up saying "The Ancient Spirits of Light and Dark Have Been Released" and your world will enter Hardmode, and will be filled with tougher enemies. This will also generate two diagonal stripes of The Hallow, and Corruption or Crimson, in a "V" pattern from the center of the Underworld all the way to the Surface (and higher, as Floating Islands in these paths will also be converted).

Hardmode enemies will begin spawning as soon as the Wall of Flesh is defeated. The stripes of Corruption/Crimson and Hallow, however, will not spawn until the message "The ancient spirits of light and dark have been released." appears.

Note: See Hardmode for more extensive information.

Achievements
Still Hungry is the achievement you earn for defeating the Wall of Flesh for the first time ( only).

It's Hard! is an additional achievement you earn for converting a world to Hardmode for the first time ( only).

Tips

 * Try not to use melee weapons if you are fighting the Wall of Flesh for the first time, because you take a sizable amount of damage from touching the Wall of Flesh or its many Hungries. If you find one however, a Dark Lance works very well with a long walkway.
 * Mobility-enhancing items, such as Gravitation Potion, Rocket Boots and various Hooks can make traversing the Underworld much easier. Similarly, items like Obsidian Skin Potions, Lava Waders, or an Obsidian Rose can mitigate the underworld's ambient hazards.
 * You may want to make a backup of your world in case you discover that you weren't ready for Hardmode yet.
 * The Wall of Flesh attempts to cover the entire Underworld cavern space by moving its eyes up and down; it orients by existence/absence of solid blocks and liquids 4-5 tiles above and beneath the eyes. That means making a bridge will make the eyes stay at constant height 4-7 blocks from the bridge.
 * Water Walking Potion, Lava Waders, Rocket Boots/Spectre Boots, or Obsidian Skin Potion are of great help in mitigating the Underworld's many lava pools.
 * Beenades are a highly effective weapon against the Wall of Flesh, especially in expert mode.
 * You can make a long wooden platform going along the underworld quite high up so the stuctures, lava and mounds of ash do not get in the way.
 * Bees Knees is a useful weapon for extra damage or use the Molten Fury with Jester Arrows or use the Phoenix Blaster.

Trivia

 * The Wall of Flesh is the only boss (excluding Moon Lord and Frost Moon/Pumpkin Moon bosses) that does not despawn based on player distance. Once summoned, it only despawns once it reaches the edge of the world.
 * When the Wall of Flesh is alive it is possible for the Guide to respawn during the battle with the Wall. Dropping another Guide Voodoo Doll will kill the Guide but won't summon a second Wall of Flesh.
 * Despite being based around flesh, the Wall of Flesh does not bear much semblance to, and was in the game long before, Crimson.