Guide:Surviving in the Underworld

Surviving in the Underworld
The Underworld is one of the most dangerous biomes in Terraria, and reasonably so; the best items are found here and the best materials mined for high tier items, such as the Molten armor set. This guide will cover how to survive long enough to gather these precious resources and go home safely, as well as an exploration guide.

In the Underworld, there are currently 6 monsters that spawn regularly before Hardmode: Hellbats, Fire Imps, Lava Slimes, Demons, Arch Demons/, Voodoo Demons, and Bone Serpents.

First Timers
On their first trip to the Underworld, players should be equipped with good armor, such as Necro armor or Shadow armor/Crimson armor, and an Obsidian Skull is a necessity. The Hellstone in the Underworld, one of the main reasons to go there, is extremely hot and will burn players on contact, if an Obsidian Skull is not equipped. Be sure to have a Shadow Orb and Torches (for more permanent lighting), because even though the lava provides some light, it's always important to be sure of what is nearby.

As for weapons, players should go with their strongest weapons, such as a Muramasa, Blue Moon, Magic Missile. For rangers, a high tier bow and at least Flaming Arrows are suggested. For more mana-focused characters, bring the Aqua Scepter along as well and fire in short bursts, if Jungle armor is not equipped, and be sure to have a Band of Starpower.

Flippers are also strongly advised because if timed right, players can swim in lava without being harmed by it, but only once. This can be a lifesaver and give players time to grapple a nearby block. Plenty of expendable blocks, such as dirt or stone, are advised for short bridging. Care must be taken when making long bridges in the underworld, as a single Lava Slime or Hellbat can catch careless players off guard and nudge them into the lava. Equipping a Cobalt Shield would eliminate this danger. Otherwise, for large pools of lava, either bring Rocket Boots and fly over them or grapple along the ash ceiling.

In the Underworld, the Hellstone Brick and Obsidian Brick "houses" with Hellforges in them are a player's best friend, as they are a relatively safe place to heal and regain mana. The bricks will block Demon and Voodoo Demon scythe attacks, but be wary, because it's possible for the scythe to damage players standing next to the wall it hits. This is where that Magic Missile comes in handy to safely kill the Demons before moving on. It's a good idea to pick up one or two of the Hellforges, as they are the only way to craft Hellstone Bars, making the whole trip worthwhile.

Demons and Bone Serpents are far too powerful to leave alive while continuing to explore. They should be dealt with as soon as possible. Hellbats and Lava Slimes can be avoided to an extent. Do not underestimate any monster in the Underworld, however, as that often ends with the player swimming in a pit of lava or torn to bits by a lone Hellbat. A Lucky Horseshoe (or equivalent, such as a grappling hook or cloud in a bottle to use to break the fall) is also advised, because there can be some large drops in the Underworld.

In the Underworld, the major treasures to look out for are the pots, chests (while watching your back and remembering you can still attack with the inventory open if autopause is turned off), Hellstone, and Fireblossoms. While at first it may not seem like it, Fireblossoms can be extremely useful in the Underworld. When combined with Waterleaf, Obsidian, and a Bottled Water, it will make an Obsidian Skin Potion, which grants you immunity to lava for 4 minutes. This is extremely useful, making lava only as dangerous as water.

As for your very first trip to the Underworld, you should focus on gathering as much Hellstone as you can and collecting as many Fireblossoms as you can find (mature Fireblossoms look like a red stalk, they're somewhat large, grow on ash and should be rather obvious). Also, you HAVE to pick up a Hellforge while you're there so you can make use of that Hellstone. Hellforges can be picked up by taking away the block underneath them or harvesting with a pickaxe.

For Return Trips
On later trips to the Underworld, players should be much more prepared and ready to fight. Don't go for extreme exploring until you have a full set of Molten armor, a Flamarang, a Fiery Greatsword (or possibly a Night's Edge), and a Phoenix Blaster or a Molten Fury. Players should also have several Obsidian Skin Potions. But even with all this gear, the Underworld is extremely tough and should be treated with caution. The Shadow Orb (item) and the Ivy Whip will be very useful (or at least a Grappling Hook, but the Ivy Whip has better speed and range).

Being more properly equipped, players can begin to challenge the the REAL Underworld. Before, players were challenged just defending themselves to mine enough Hellstone to make decent gear. Now, go on the offensive. The goals are to find as many Shadow Chests as possible, trying to find Sunfurys, Flamelashs, and a Dark Lance.

Kill any Demons along the way, as they may drop the rare Demon Scythe as well. Breaking pots can be very useful, as some have powerful Hellfire Arrows in them. Also, stop immediately to pick up any Fireblossoms to make more Obsidian Skin Potions. Discard unneeded items, such as Glowsticks and Bombs. Quite a few will drop from pots. Enabling Autopause is recommended for those who don't fight well with the inventory open.

Pots will also have potions, sometimes even Obsidian Skin Potions, saving the trouble of making more back at base. On these exploration trips, Hellstone is by no means a priority, since players should already have all the Molten gear they need. The only use for Hellstone Bars is money.

Players should be sure to keep an eye on their health, so that it doesn't drop too far below 200 (assuming 400 maximum health). Bring plenty of potions. If overwhelmed, players can wall themselves in somewhere safe to regenerate health and mana. However, a Bone Serpent or Fire Imps still pose a danger even then. Be sure not to wall in a small area, but allow enough room to move around and dodge if needed.

It may be wise to to use one slot in the hotbar to keep the Magic Mirror handy, in case things go badly. Know which hotkey it is on or which weapon it is near if scrolling. There's no shame in backing out of the Underworld to keep the money gathered down there. A large part of surviving the Underworld is preparation, but even more important is practice and experience. Always keep trying, because failure is just a chance to learn what went wrong and take the extra precautions to make sure it doesn't happen again.

Combat Survival in the Underworld
This section will be divided in two parts; the first bullet will be a strategy for mining Hellstone, while the second will be a strategy for exploration runs.

Hellbat
 * Hellbats are very common in the Underworld, but once you have a good tunnel going there's a chance that many Hellbats will spawn on-screen, but unable to reach you. This is VERY good, because it stops other more dangerous monsters from spawning like Bone Serpents and Demons. There is the occasion that one or two will reach you while mining away. Simply kill it with your sword of choice, making sure it does not get near you because it will bounce around the walls and hit you a good few times should you miss enough. Collect the coins and move on with life. The Night's Edge with Molten armor will often one hit these monsters as well.
 * Hellbats are one of the most annoying monsters that appear in the Underworld. They spawn very commonly and are quite small. A good strategy is to hit them with the Flamarang, but this does require some accuracy. If you don't feel you can make the shot, use an Aqua Scepter, Flamelash, Magic Missle or a good old fashioned sword to get the job done. On crowds, the Night's Edge and Fiery Greatsword work wonders with the right timing. If you just can't get the time right, use a Muramasa to combat these annoyances.

Lava Slime
 * Lava Slimes, since 1.0.6, are of no threat to your mining operation. Simply deal with them as you would any other slime. Their damage is low as well as their defense.
 * Lava Slimes have been completely simplified in terms of difficulty since the 1.0.6 patch. They are quite harmless, their best hit at 2 with Molten armor and an Obsidian Skull you should really have. The only part worth noting is that they are launched in lava, so while you're passing over a pool of lava, stay alert of Lava Slimes flying up at you. Other than that, choose your weapon and annihilate them.
 * Lava Slimes in expert mode can be a pain because they spawn lava when they die, so try not to get to close to them when you kill them, use a ranged weapon like a flamarang or pheonix blaster.

Fire Imp
 * Ah, the infamous Fire Imp. Older players who have been playing this game since its release have grown to hate this monster with a passion, especially when mining. Since the 1.0.5 patch came out, which was the first patch that added more monster content to the Underworld, Fire Imp spawn rates have been well lowered to make room for the new monsters. You will encounter quite a few of these while mining, but because there is more chance of a Hellbat to spawn than a Fire Imp, simply hit their fireballs then go up to them, say hello and kill them. They fire 3 fireballs, then teleport to another location. If you can hit them once, they stop everything and don't move for about 2-3 seconds after each hit, making them defenseless to any attack you choose. If you're not fast enough, however, they will teleport away and start firing again.
 * Because Hellbats and Lava Slimes are extremely common now, Fire Imps are actually a rather uncommon spawn while exploring. They often spawn behind you, but you should keep moving while dodging their fireballs (which pass through walls) until they get in a more reachable position. Then kill them like you would a green slime that doesn't move with 80 health and decent defense.

Demons/Voodoo Demons
 * Since Demons and Voodoo Demons both follow the same AI, they should be dealt with the exact same way: walling off their entrance and leaving a small hole so they can't hit you but you can use your Magic Missile or, if you have it, the Flamelash. If you're feeling gutsy, you can make it faster by simply hacking away at them, but Demons and Voodoo Demons are the hardest hitting monster in the underworld, able to hit pretty high no problem with a single scythe. They should be treated with high caution anywhere in the Underworld.
 * Demons and Voodoo Demons are not entirely that common in the Underworld, but they do occasionally spawn in groups, and that is very bad. When a group of Demons or Voodoo Demons spawn, your best bet is to get to a spot where you are somewhat defended by bricks and snipe them with the Magic Missile or Flamelash. The same strategy works for a single Demon, but does leave you open to attack by more versatile monsters such as Hellbats and maybe even a Bone Serpent that are bound to spawn with only one Demon. These monsters should be treated with extreme caution. Especially for the Voodoo Demon, as killing him above a pool of lava may cause the Guide Voodoo Doll it drops to fall in the lava, causing the Wall of Flesh to appear. As you get more experienced, try the Night's Edge with Molten armor on them, flying up to them with Rocket Boots and running away as it is about to spawn its scythes.

Bone Serpents
 * Bone Serpents have the power to single handedly wreck your mining operation. They're big, they're fast, they take a lot of hits, but remember: it is much better to be hit by a body segment than the head. The head does large amounts of damage, while the body segments do significantly less. This monster is the whole reason you brought the Blue Moon or Sunfury. These two weapons work wonders on the Bone Serpent, because they do good damage on almost every single part of his body multiple times. While you're mining, you will take some hits from this monster, but be sure to keep damage at its lowest and run when you hear that tunneling sound it makes so you can prepare to fight back.
 * Bone Serpents, when alone, are not too much of a threat. A simple strategy that works well is to jump up and use Rocket Boots to keep yourself above it while smacking it with your Blue Moon or Sunfury. Unfortunately, this monster loves to jump in on a Demon party in progress. In this occasion, you must kill the Bone Serpent first. Bone Serpents cause you to stay in a predictable area, making you an easy target for Demons. While the Bone Serpent is on-screen, focus Blue Moon and Sunfury attacks on him. When he is gone, switch to the Magic Missile or Flamelash to fight the Demons. Be sure to switch right back to your flail when you hear that tunneling sound and you should be fine.

Hardmode Enemies

Lava Bat

Lava Bats are the Hardmode version of Hellbats. They don't pose much of a threat, but don't let them get in groups, as they hit for 50 damage. You can use pre-hardmode weapons against these bats and kill them easily, but as you likely have more powerful weapons now, a Phasesaber or a ore sword are the best against them. They should be treated the same as Hellbats.

Red Devil

The true danger of Hell during hardmode, Red Devils are Demon-like enemies, except much tougher. They are one of the deadliest enemies in the game, with 600 HP and being able to do 130 damage with their trident attack. It's suicide to go up against them in Melee combat, so it's best to have a Hallowed Repeater for ranged attackers, and a Crystal Storm as they both attack quickly so the Devil doesn't have a chance to attack back.

Miscellaneous

 * The Hellstone Brick or Obsidian Brick houses can be used to get quickly to a lower elevation if it is large enough, with easy access to pockets of Hellstone.
 * For information on mining hellstone in your first trip to the Underworld, visit the Hellstone Mining guide: Guide:Mining techniques.