Guide:Surviving in the Crimson
This means the page will walk you through a specific task, strategy, or enemy/boss fight.
The Crimson holds the same role as the Corruption, being more difficult to traverse than other surface biomes due to its enemies being more aggressive. Compared to the Corruption, the Crimson has easier-to-navigate terrain and no counterpart to the collision-ignoring Devourer, in return for a greater focus on grounded enemies.
Traversing the Crimson may be important earlygame to explore the surface and find other biomes, especially if the world starts with Crimson on both sides of the player. Crimson Hearts can also provide useful loot earlygame and summon the Brain of Cthulhu, which can be killed to spawn a meteorite and get Tissue Samples for Crimson armor and a Deathbringer Pickaxe, which in turn allows you to mine Hellstone. In Hardmode, the Underground Crimson can provide Souls of Night and Ichor.
Terrain
Most of the terrain consists of whatever biome the Crimson is generated over, converted into Crimson blocks. At the center of Crimson patches are chasms, which generate as "caves" made of Crimstone with tall, horizontal entrances gradually sloping down into a large circular cavern with more tunnels spreading away. In each of these lower tunnels is a Crimson Heart, which can be broken with either bombs or a hammer.
This makes the difficulty of traversing the Crimson dependent on the natural terrain it generated over. Platforms are very useful both for crossing potential gaps and dodging enemies, while Rope is a convenient option for climbing over chasm entrances you do not want to explore yet.
Crimson grass will grow thorns over time, which will damage the player when touched. You can break them with any weapon or tool, or jump over them with the help of platforms. It will also grow 
Vicious Mushrooms, which can be harvested and crafted into Vicious Powder, and 
Deathweed, which can be harvested during a Blood Moon or Full Moon, or using a Staff of Regrowth. Trees grown on Crimson grass will provide Shadewood, which provide stronger alternatives to normal wooden equipment early on, particularly the hammer.
The entrance tunnel to a Crimson chasm is always sloped downward, and the entire chasm is covered in background walls. The downward slope can sometimes cause issues with fall damage, while the background walls mean platforms and Rope can be placed anywhere inside. This allows for quickly breaking your fall with a platform when entering the chasm, or jumping up and placing platforms below you to quickly leave the chasm.
Crimson Hearts
Each Crimson chasm contains several Crimson Hearts, surrounded in Crimstone. Early on, you will not have a pickaxe strong enough to mine Crimstone, but explosives and Purification Powder can be used to reach them. There, you can smash them with a hammer or with another explosive.
Destroying the hearts will cause the following effects:
- When the first Heart is broken, Goblin Invasions will start spawning naturally once a player has 200 max health or more.
- A usable weapon, accessory, or light pet will drop. The first Heart will always drop
The Undertaker. - Every third Heart smashed will summon the Brain of Cthulhu in addition to its item drop.
The game will produce a message with each Heart smashed, with messages depending on whether this is the first, second or third Heart smashed in a cycle:
- First: "A horrible chill goes down your spine..."
- Second: "Screams echo around you..."
- Third: "Brain of Cthulhu has awoken!", accompanied by the boss' spawn.
The Brain of Cthulhu will despawn immediately if you teleport out of the Crimson after it spawns, such as with a Recall Potion. This lets you safely break Crimson Hearts and collect their loot without worry. There are a finite number of Crimson Hearts generated with each world, but the Brain of Cthulhu can also be spawned using a Bloody Spine crafted at a Crimson Altar without limit. The main downside to smashing Crimson Hearts is the chance of natural Goblin Invasion spawns. For that reason, you should avoid smashing Crimson Hearts until you feel ready fighting a Goblin Invasion[a].
If you want to fight the Brain of Cthulhu, consider checking out Guide:Brain of Cthulhu strategies for more information on that fight.
Pre-Hardmode
In Pre-Hardmode, Crimson enemies tend to be slow, and barring Crimeras, none of them can fly. This means avoiding enemies is a strong alternative to fighting them, especially if you have to cross a patch of Crimson early on.
Platforms can be used with Cursor inteligente to place stairs, which you can then walk up and jump off of over enemies. If you have a Cloud in a Bottle, this can help you jump over enemies as well, and gives you more control for dodging Crimeras.
- Crimeras have low knockback resistance, but fly around and can be hard to hit. Bows with Flaming Arrows or Frostburn Arrows are good options for hitting them.
Face Monsters and 
Blood Crawlers have much higher knockback resistance and damage compared to Crimeras, but are less mobile. Strong weapons with good knockback like Grenades, an Emerald Staff or stronger, or a Gold Broadsword or Platinum Broadsword can help cut through these enemies later on.
- Blood Crawlers are 7x more common in chasm tunnels than outside, and have more knockback resistance and mobility as they crawl along walls. You can also trap them in solid blocks to move past them.
Vicious Goldfishes uncommonly spawn in pools of water in the Crimson. They swim back and forth aimlessly until you enter water, after which they will start pursuing you until you exit the water. While not completely harmless, even a Wooden Sword or Bow is enough to deal with them.
Vicious Goldfishes will only drop coins, but the other pre-Hardmode Crimson enemies will drop 
Vertebrae and rarely the 
Tentacle Spike. Crimeras rarely drop 
Burgers. If you want Vertebrae, it is much easier to farm them in pre-Hardmode, as most Hardmode Crimson enemies do not drop Vertebrae at all.
Consider using bombs to collect large amounts of Crimstone from a chasm entrance. Crimstone can be used to make an artificial Crimson biome or farm Crimson enemies later on, and can also be used to grow Deathweed in a pinch.
When exploring a chasm, speed is key. If you move quickly, it is possible to reach the inner cavern without encountering a single enemy, and if you take a long time traveling down, you could have many enemies spawn in the tunnel to block you. The main reason to enter a Crimson chasm is to break a Crimson Heart, so make sure you bring Bombs, Dynamite, or Purification Powder as a way to reach the Crimson Heart and more explosives or a hammer to break it.
Use Glowsticks or Flaming Arrows to light up the tunnel ahead of you. Do not jump blindly if you cannot see the floor, or you may jump into the larger central cavern.
For the central cavern, use Rope to glide down or platforms to catch your fall. Hooks or extra jumps can also help with going down, but need to be timed correctly.
In the central cavern, there is a lot more space for enemies to reach you, and for you to move around in. You can go down the various lower tunnels to reach Crimson Hearts to smash them, and the large central cavern provides space for an arena for the Brain of Cthulhu, if you choose to fight it.
Hardmode
With the start of Hardmode, a diagonal strip of Crimson biome will appear on either side of the world, and Crimson will start naturally spreading over time from all Crimson blocks to all convertible blocks.
The 
Pwnhammer you got from killing the Wall of Flesh can be used to smash Crimson Altars, which will generate new Hardmode ores, which are very important for early Hardmode progression. The Crimson chasms from Pre-Hardmode are the best places for this, with a high density of Altars to smash. 9~12 Altars smashed can be a nice goal to start with, providing around twice as much ore as smashing 3 Altars. Altars are valuable crafting stations, but you only need 1 Altar for this, for which you can either choose to not smash an Altar, or find one elsewhere in the world, outside the Crimson, and put a Pylon there.
Each Altar smashed will spawn 
Wraiths, so it is best to move quickly when smashing them. Smashing any Altar will allow Pirate Invasions and mechanical bosses to spawn naturally, but its benefits are well worth it.
Underground Crimson
Besides Altars, the value in the Hardmode Crimson lies in the cavern layer, within the Crimson portion of the Hardmode V spread. Each enemy here has a 1/5 (20%) / 9/25 (36%) chance of dropping a 
Soul of Night, while 
Ichor is dropped by Ichor Stickers and Tainted Ghouls. Both of these items are valuable crafting materials.
Hardmode ores produced by smashing Altars are easier to mine in pure caverns, and, if the player is willing to take a bit more time, an enemy farm will provide a safe and efficient way of getting the valuable enemy drops from the underground Crimson.
There are many new enemies for you to deal with: the Herpling, Floaty Gross, Ichor Sticker, Crimslime, Blood Jelly, Crimson Axe and very rarely the Crimson Mimic.
Herplings are fast, tanky, and have high knockback resistance, with lots of contact damage. They can easily kill a new Hardmode character. However, they can't jump very high, so using a Hook or Wings to stay above them will make them much easier to deal with; alternatively, they also float on water, letting you stay underwater to avoid them.
Floaty Grosses move through blocks to attack the player, with a small chance to inflict the 
Weak debuff on hit. They have low knockback resistance, but can potentially be defended by walls; weapons that extend into walls like whips or the Night's Edge are good options for fending them off. Due to their translucence, they can be hard to see while spelunking, making Hunter Potions especially valuable for spotting them.
Ichor Stickers are very common and very dangerous in open spaces. They have more health than the other enemies, and they shoot an accurate Ichor spit that does a lot of damage and inflicts the 
Ichor debuff, which will reduce defense by 20. They can't attack through blocks, though, and long-range fast projectiles like from the Phoenix Blaster can stun them for long enough for you to close the distance and kill them.
Crimslimes and 
Blood Jellies act just like a regular Slime or Jellyfish, but with higher stats. Their limited mobility and range make them less threatening than other enemies, but Blood Jellies can electrify in Expert Mode and above and move very quickly in water.
Crimson Axes are an uncommon enemy that can move through blocks and can inflict 
Cursed on hit. This makes them potentially the most dangerous enemy to be hit by, but due to low knockback resistance and tendency to stop moving when hit, they can be treated similarly to Floaty Gross. They are very easy to see.
Crimson Mimics are the Biome Mimic of the Crimson. They are passive until damaged by the player, but have immense health, damage, and the ability to move through blocks. Their loot is very valuable, and there are a number of ways to defeat them, such as with decent open space, but depending on the situation you likely want to leave them alone. You can craft 
Keys of Night later to summon them manually in a more open area.
Alongside these enemies, red Pigrons start spawning in crimson Ice biomes, while five new enemies can appear in a crimson Desert: Blood Mummies on the surface, along with Dark Lamias, Tainted Ghouls and Desert Spirits underground. Flesh Reavers can appear on the surface during a Sandstorm.
Pigrons can become nearly invisible and appear when they are about to attack you, but make audible growls as they approach. Any weapon that can attack through blocks can be used to kill them. Pigrons may drop valuable Bacon.
Blood Mummies will start running faster once reduced to 50% health or lower, but otherwise behave similarly to Zombies. They can drop 
Dark Shards, which can be used to craft the Dao of Pow or the Onyx Blaster.
Dark Lamias aggressively chase you, attempting to deal contact damage. It is best to carve out a larger area in the Underground Desert, preferably in pre-Hardmode, so that they are less likely to reach you.
Tainted Ghouls will inflict the Ichor debuff upon contact, making them a bit more threatening in close quarters. Any long-range weapon can be used to kill them. They may drop Dark Shards.
Desert Spirits are by far one of the most dangerous enemies that can be found in the crimson Underground Desert. They will stand still and sometimes teleport, casting homing projectiles that pass through blocks and explode after a few seconds. Be sure to fight them in an open area, and keep in mind that only the explosions deal damage. They may drop the 
Desert Spirit Lamp, used to craft the Spirit Flame.
Flesh Reavers "swim" inside sand blocks and jump out to deal contact damage, although they cannot swim through any other blocks. You can take advantage of this by baiting them into jumping out of the sand and into non-sand blocks where they become more vulnerable to attack. The best way to deal with them, however, is to place platforms above a height that they cannot reach, and attack from above with any weapon that shoots projectiles. They can only jump up to a height of 16 blocks for reference. Flesh Reavers can drop Dark Shards and Shark Fins.
Footnotes
- ↑ Staying below 200 max health also works for this, but is much more cumbersome. Reaching 400 max health is much better than any item a Crimson Heart gives you.
