Defending one's house is important - NPC survival relies on player techniques. There are a few techniques for different occasions, such as Blood Moons, Goblin Armies, as well as basic defense strategies.
Constant threats will terrorize a player's home including:
- Blood Moon: Zombies gain the ability to open doors and will relentlessly attack buildings occupied by the player alongside Demon Eyes until day breaks. Regardless of how many NPCs they have, the player has to keep enemies from entering their base.
- Goblin Invasion: Not as common as a Blood Moon, but more dangerous. 80 goblins, plus an additional 40 per user with 200+ hp, will spawn and attack the player's base. The biggest annoyance is the Goblin Sorcerer, who will teleport all over the area (including inside homes) and can shoot through walls. Also the Goblin Warrior can break down doors allowing smaller Goblins to move in.
- Wraiths: After the Wall of Flesh is defeated, these will spawn at night. They are capable of passing through solid blocks, but can only hover up to three blocks up. Constructing a home suspended at least this distance above the ground will be sufficient to stop them from entering.
- Possessed Armor: After defeating the Wall of Flesh, these will spawn at night. They can open doors on any given night.
- Werewolves: After defeating the Wall of Flesh, these spawn at night during a Full Moon. They can break down doors (which causes them to drop as items) in order to let other monsters into the player's home.
- Pirate Invasion: Has a chance to spawn after the wall of flesh is defeated, at least one altar is destroyed, and if the character has at least 200 max. All the types of pirates deal heavy damage to early hardmode characters.
- Solar Eclipses: A dreadful event that lasts for a whole 15 minutes (as opposed to the 9 of a Blood Moon) and spawns hordes of extremely dangerous enemies, most notably Vampires, which are fast, strong, and can fly to fit through tight spaces.
One-Way DoorsPlacing a block (or a torch) of any material in front of the door will keep it from being opened by zombies or goblins, though it'll also prevent the player from using the door. On the other hand, placing a platform, torch, or another background object (except for a wall) behind a door will prevent it being opened from the outside, yet still, allow passage through it. Opening the door from the other side by players is simply done by facing away from the door then using it. This won't stop Goblins from breaking down the door but will prevent Zombies from opening it (this doesn't work in the mobile version of Terraria as Zombies can open doors in both directions).
Placing sand on the opposite side of a door so that it will fall by gravity will damage every monster it lands on and locks down the door. Repeating the process of placing the sand then mining it back is a very safe way of dealing with monsters knocking on doors.
Suspended DoorIf doors are suspended above a flat area of land by just a two by one tile rectangle, Zombies will be unable to open it. Goblins will still be able to break it down though. However, if the door is suspended 2 or more blocks, even they won't be able to break it down. Fortunately, NPCs can still use a door suspended by 2 tiles with ease.
Zombie Pits and Flying Enemy Cages
- Main Article: Traps
Both of these are used to trap certain enemies. In the Zombie Trap's case, it's Zombies and goblins, and in the Flying Enemy Cage's case, it's any flying enemy (except for bats, harpies, and demons), including Demon Eyes, though it can be modified to trap slimes as well. Both traps can be utilized alongside other defensive mechanisms such as sand barriers, suspended doors, and even lava moats.
These types of traps can be set up right at the start of a new world for both safety and the ability to easily kill and loot early enemies. This is particularly useful when starting out in Hardcore Mode. At left is an example of an efficient structure that you can build before the first night.
Thrown Weapon GlitchA glitch in version 1.0.4 with all the thrown weapons (Boomerang, Shuriken, Ball O' Hurt, etc.) allowed the player to throw them through the door as long as they were aiming at the handle of the door or lower. This didn't work with melee, gun, or bow type weapons. The only exception being the Star Cannon, which could shoot through 1 block wide walls. This was due to the distance between the player and the projectiles' spawn area.
Digging a Deep Pit in Front of Your DoorA simple defense would be to dig a ditch underground that is too deep to jump out of, yet retains a way for a player to escape. A simple ditch would be dug out more than six blocks down, four blocks wide, with a ceiling of no more than four blocks high, while leaving a small area on the side of the pit opposite of your door so a player can jump up. If this is built properly, the only monsters capable of entering a house are the Sorcerer and the Demon Eye (most Goblins cannot enter because nobody can jump far enough with such a low ceiling). To remedy the Demon Eye problem, simply put a door on the other side of the ditch, as demonstrated on the left. Furthermore, if you dig a little farther until the Zombies can walk off screen, they will automatically despawn after enough time of being off screen, so the player doesn't have to worry about risking their life to kill a horde of Zombies.
Suspended HouseBuilding a house in the air prevents any sort of land monster from entering the house regardless of their ability to knock down doors. Flying creatures can still be a problem but are easily nullified with platform traps and doors. Building a house like this is completely impenetrable except by Sorcerer, Worms, or bosses.
As seen in the screenshot on the right, only one Zombie is allowed to spawn despite Blood Moon due to how many Demon Eyes are trapped. In addition, the player can fight on the ground with melee or from the central "airlock" of the house with ranged weapons. The only issue with this type of house is it can be detrimental to one's sense of gravity. This issue can be countered by making 2-4 pillars made of any wall below the house (check the picture to the right) or by using cloud blocks.
Trick the ZombiesThe main feature of this structure (#2 in the image) is that this exact design is accessible by players but tricks the zombie AI into jumping back down the hill. It will jump up against the base-side of the wall a few times, but not high enough. Eventually, it will jump higher, but backward away from the base, up through the platform and over the block, back down the hill. This has not yet been tested on goblins. Optionally this could be converted into a horizontal falling-sand block (#1 in the image). To make it easier to access a base once the player has a Grappling Hook, some wood platforms could be added on the outside (#3 in the image).
No DoorsAnother trick is to have no doors. Though this makes houses ineligible to have NPC's live in it, this method makes a fortress with little work. To create a house with no doors all one must do is build a house with a pit underneath and a staircase-like shaft leading up from the pit. Then build a long shaft leading from the staircase-like shaft straight down however far the player wishes, as long as zombies, goblins, and other monsters cannot jump up into the home. This method allows for much growth after the initial building of the tunnel/shaft system. It also works with many house types.
Simply barricade a door during a Blood Moon or goblin army. This strategy always works and requires almost no resources. However, this will not allow the player to build monster farms or prevent goblin sorcerers from teleporting in.
To create this all you need is wiring, a trigger (p. plate, lever, etc.), a door, and a timer (the faster the better). Place your door down wherever and place wire directly in front and in back of the door, hook the wiring up to your trigger (switches are usually better for this) and place the timer somewhere in the wiring. Activating the trigger will now make sure if the door gets opened it automatically closes. While this won't permanently keep away blood moon zombies, it will delay them and the noise may alert you to them. Combine this with a pit and they will have great difficulty entering.
Active Stone Walls
Build active stone blocks in front of all doors (including NPC's doors) and hook them up to one single switch. When there is a Goblin Invasion or a Blood Moon, the player can flip the switch and turn all of the blocks on. This prevents the respective mobs from opening doors. As of patch 1.2, it is also possible to use Actuators with Stone Blocks to do this.
Similar to the Active Stone Walls, simply place any object in front of a door, and Zombies (And most likely Goblins) will keep trying to break the door but will fail. Note that the only way to get in and out through that door is by opening it from the inside, which will block NPC's and other players from getting in your house if that is the only door you have on that side.
To create a lava moat, dig a deep pit near your house, on both sides. Make it long enough so enemies cannot jump over it, and deep enough so enemies can not get out of it. Fill it with lava, the more the better. Then cover the top of it with active stone walls, so it acts as a bridge. Whenever an enemy comes, they will fall into it and die. These can be used alongside other mechanisms such as darts, which can inflict extra damage to harder enemies. This doesn't protect against flying enemies.
The Essentials in Building a More Secure Base
There are ways to keep a base locked down tighter than a prison. Make only two entrances to the base (via door) on either side. Depending on whether or not the player makes towers, they can leave these doors open.
The screenshot shows the doors and how everything is completely symmetrical. Have a simple layout and add aesthetic appeal later when the base is functional. The major defense against basically all enemies is to have some type of block that stands out from all the others and put it above the doors, then put at least three blocks of sand above it. One can now leave the door open almost 95% of the time. Make sure that the door is opposite of where the sand is, otherwise the sand will just land on the door and sit there.
One can also add small cubes to the sides of their house in front of doors, and fill them with lava. Dig a six-block-long trench below them. When attacked, the player can destroy the bottom block of the cubes. The lava will create a moat that will not destroy items, although if the trench is one block deep into the ground and goes all the way to the door, then Zombies will not be able to open it anyways.
If a player wishes to farm enemies personally, they could construct towers with an overhang made of wood platforms facing the outside of the tower. The player could optionally use the sand method for their doors as well. The land should be flattened around 20 blocks outside the tower to accommodate the incoming mobs. If done correctly, the only enemy able to get in would be occasional Demon Eyes. The player should be able to move around a bit in almost complete safety and hit all enemies with ranged weapons. Any ranged weapon will do but something that is quick and does not consume ammo is the best bet, as well as good penetration so that it will pass through many enemies at once. With this technique, the only thing that might be able to kill the NPCs are enemies that teleport and/or pass through walls.
Another technique that can be used is attaching two bunkers, as shown here, to the player's home. Simply by making two boxes on the sides of the house 4 blocks high with a 2 block gap, the player could use any weapon to defend their house. Then put the doors into the house above the boxes. As long as the player remains on the bottom floor, monsters will not jump onto the part with the doors, and they can stand inside the box and swing a sword or shoot a ranged weapon through the gap.
If the player has managed to get to the Dungeon, they can actually mine the Spikes with a Hammer to put on their base. The spikes themselves will not actually harm monsters but can and will hurt players/NPC's, the only real use for spikes is either aesthetic purposes or PvP.
Sand Shell Method
A much more effective Blood Moon/Goblin Invasion defense system is shown here where the player breaks a torch and sand falls on the entire home, blocking off all entrances. The player can make the sand as tall as necessary depending on how many entrances the home has. However, setting up the system is comparatively tedious, as is cleaning it up.
A good way of taking out Zombies, Slimes, and Demon Eyes in relative safety is to make a sniper nest shown in the picture to the left. This allows the player to shoot straight, down, and up at their enemies, while the nest itself prevents said enemies from reaching the player. When paired with other defenses, like suspended doors and zombie pits, you could protect your home from even Blood Moons or Goblin Invasions, assuming that the player has enough ammunition for whatever ranged weapon they decide to use. Or just make their own nest.
Tower Method of Self-Defense
Although it utilizes a similar method to the floating base, it is connected to the ground. The tower can be locked down by triggering sand traps to block the bottom entrances of the tower. The tower uses two Flying Enemy Cages to allow capture and harvesting of Demon Eyes (and Eaters of Souls). The advanced versions of the tower can use a secondary sand blocking system, and can also incorporate Zombie Pits and/or Lava Traps to deal with Zombies and Goblins.
Double-Door Pit Trap
As the name implies, this trap consists of two doors with a two block wide space between them; this space is occupied by a pit that is too deep to jump out of without assistance. Due to this, it would not be wise to attempt this trap without a Grappling Hook, Cloud in a Bottle, or a pair of Rocket Boots. The concept of the trap is that enemies will be able to enter through the first door, but will find themselves falling into a hole when they attempt to break down the second. The player can jump over the pit by opening both doors at once and jumping straight through; this is not an easy task with a low ceiling, so make sure that you own one of the previously mentioned items.
Water U-bend GateBy constructing a U-shaped structure and filling it with water, you can prevent most enemies from getting from one side of the U to the other yet still allow players to do so (it will not work on enemies that can teleport or burrow). For some reason, players can jump higher in water than jumping enemies - they can jump out of the water to a platform up to 7 blocks high (enemies can only reach 4 or 5) with a normal jump. Flying enemies and Slimes will not enter the water at all.
Since there is no equivalent to a reverse wooden platform that prevents flying enemies from passing up through the bottom of it while letting players through, this is one of the few reliable methods for preventing enemies from getting up into the bottom of a base that has underground tunnels connected to it or is suspended in the air. For example, placing this structure at the top of a hellevator attached to the bottom of a base can prevent enemies using it as a way in. The obvious alternative is a normal door, but this method doesn't require the extra step of opening and closing the door to get through it.
Double/Single Outer Walls
These can be built with any number of walls but usuallyare built with only one or two walls. These are very good for defending larger structures especially if you use doubles. They are two walls as tall or taller than the player's house with a door at the bottom and torches on the sides. They are very useful for a situation like if a Blood Moon starts and the player needs to get home as fast as they can. The double door on the walls would likely give the player enough time to block off the doors before the zombies get into their house.
The lava pit is constructed for enemies to fall into. These can be hard to build for beginners since the player needs access to lava to make. If the player wants to collect items that the monsters drop, they need to make sure that they put only one Lava Bucket in each pit (1 bucket of lava x 6 blocks wide = no item burning). Otherwise, the items will be destroyed.
The player can make a bridge over the lava with active stone blocks by placing the blocks over the lava pit and wiring them up to a switch. When night comes (or the player leaves the house) turn on the switch. Whilst the switch is active, non-flying mobs will fall through the blocks into the lavaAdditionally, if the house is above the ground, the lava trap can go all the way under the house on both sides. NPCs will simply stay inside if there is no place for them to walk to outside the door.
Wire TrapsAs of patch 1.1 wires can be used to build traps, such as dart traps, that can be triggered by enemies. These kinds of traps are relatively easy to set up and can be extremely useful in all situations, from blood moons to goblin invasions.
The picture on the right shows a base with a 1-second timer attached to everything ranging from super dart traps to spiky ball traps and lava pools on both sides.
The Lockdown Device is a simple, but very effective, device that prevents all monsters (except for monsters that dig/pass through walls) from entering any house. The player needs to lay down a wireline that goes underneath the entire area that is to be defended and place a wire in each building that needs to be locked down. Then they need to put a wall of active stone blocks one block away from the outside doors of each house. They could optionally attach it to the house right above the door if being used for PVP to keep lava out. Finally, they need to wire the levers and the active stone blocks to the wiring they laid out in the first step. With this setup the player can activate a citywide lockdown from any building.
Dart Trap FortressIf the player can get their hands on enough Dart Traps, wires, and pressure plates, then they can design a dart trap defense that encompasses the entire base. When this many dart traps are wired up, any player can effectively fight blood moons, goblin armies, and frost legions from the comfort of their home.
Leaf Crystal Defense
A full set of Chlorophyte Armor summons a permanent Leaf Crystal above the player which automatically attacks enemies on screen. By standing under a low ceiling so that the Crystal is outside, a player can just let it deal with the enemies. This, along with other automated defenses, makes for a great way to survive invasions.
Monsters that are able to phase through walls might still cause damage, though.