Like the Corruption, the Crimson is a difficult environment to survive in with its strong enemies that can be very troublesome for new players. Exploring the biome is not required to progress in the game, however it is full of useful items so it is recommended to visit due to the Deathbringer Pickaxe being required to mine Hellstone.
- Have at least 200 health. Magic users should have at least 100 Mana.
- It is recommended to have at least Silver armor or Tungsten armor. Gold armor or Platinum armor are better although much harder to obtain.
- Melee users should bring Gold Broadsword or Platinum Broadsword at minimum, or Blood Butcherer if Eye of Cthulhu has already been defeated, or enough ore is found.
- Ranged users should bring a Gold or Platinum Bow with Frostburn Arrows. They are easy to craft and farm, as Ice is very easy to obtain, and Torches can be bought from the Merchant.
- Magic users should bring at least Sapphire or Emerald Staff. Ruby Staff or Diamond Staff are the best available.
- Throwing users should bring a bunch of Throwing Knives, as they aren't too difficult to obtain. Grenades can also be used, although they may damage the player if used recklessly.
- Bring with you at least a half stack (15 out 30) of Lesser Healing Potions. Some Lesser Mana Potions should be brought as a Mage.
- A Grappling Hook is highly recommended, as it can greatly help you navigate the chasms.
- It is also good to bring Rope or Platforms, as they help when climbing out of the chasms.
Exploring the Crimson
Unlike the Corruption, the Chasms consist of an entrance to a "cave" instead of multiple, deep pits. This makes exploration easier, although the enemies are more varied and more dangerous.
- The Crimera is the crimson-counterpart of the Eater of Souls. They will hover above you, and sometimes swoop down and attack you. Like their corruption counterpart, they will not submerge in water, and can overwhelm you if they're in a pack. Ranged weapons can easily deal with them, like a good Bow or a Boomerang.
- The Face Monster is like a Zombie, except taller, and has lot more knockback resistance. This makes it harder to kill with close ranged weapons.
- Blood Crawlers are the main threat when exploring. On the surface, they can be considered a weaker version of the Face Monster, but in the cave, they can crawl on the walls, making them a lot less vulnerable to knockback, and harder to deal with overall. They are the most common enemy underground, and they will make it hard to explore the cave. Ranged weapons or a Spear should be used.
Once inside the cave the goal is to smash the Crimson Hearts found at the bottom of them. They let off a faint glow which will allow the player to easily locate them, but can only be reached initially by use of Bombs or Purification Powder purchased from the Dryad. They can then be destroyed by using a Hammer or Bombs.
- Note that the Crimson, unlike the Corruption, doesn't have any enemy capable of going through blocks or shooting projectiles in Pre-Hardmode. This makes the strategy of rushing to smash the Crimson Hearts much more viable, as it is possible to just surround oneself with solid blocks and slowly, but surely advance deep underground.
- It is sensible, when creating tunnels this way, to place solid blocks, as to form rooms, inside the tunnel itself, as enemies could still spawn off-screen INSIDE the tunnel, leading to a potentially deadly confrontation for an unprepared Player.
Destroying the hearts will give you the following messages:
- When the first Heart is broken, the text "A horrible chill goes down your spine..." will appear;
- When the second one is broken, the text "Screams echo around you..." will appear;
- When the third one is broken, the Brain of Cthulhu will spawn, with "Brain of Cthulhu has awoken!" appearing.
Just like the Corruption, a diagonal strip of Crimson biome will appear on either side of the world, and any Crimson block will start spreading.
The player will also be able to use the Pwnhammer dropped by the Wall of Flesh to smash the Crimson Altars. Destroying them will generate new ores, which are almost mandatory to progress in the game. Smashing 9-12 Altars will be more than enough for most of Hardmode, since more than that won't generate too many new ores. Breaking altars will swarm the player with Wraiths, so they should be very quick when doing so to avoid dying.
Altars are also crafting stations, so it isn't a bad idea to leave one for the special recipes requiring them.
Note that smashing Altars has a chance to infect a random block in the world. This will barely affect the overall spread, but it can infect areas the player tried to protect.
After the altars are smashed, the Crimson should be avoided until better gear is obtained, since Pre-Hardmode weapons and armors won't be enough to deal with the new enemies.
The Underground Crimson
As the bare minimum, the best Pre-Hardmode armors of the player's class should be used, such as Molten armor, Necro armor, Jungle armor or Wizard set and Bee armor for Melee, Ranged, Magic and Summoner users respectively. Armors made with Hardmode materials should definitely be used if obtained.
The player should also get a strong Hardmode weapon before venturing in. There are many choices depending on the class used:
- Melee users should grind for an Amarok in the Snow biome as it can be easily obtained at the beginning of Hardmode and will last until the Mechanical Bosses are defeated. A Sword or Spear made with the new ores will also do fine against them.
- A Ranged character is better off with the Clockwork Assault Rifle dropped by the Wall of Flesh or a Shotgun. The Repeaters made with the new ores will also do just fine against them.
- A Mage may want to farm for a Sky Fracture, made with a Hallowed Desert's materials. They can also fish for a Crystal Serpent, or just use the Laser Rifle dropped by the Wall of Flesh until better weapons are obtained.
- Summoners will need a Spider Staff and Queen Spider Staff, made with Spider Nest's materials.
With good gear, it is now a lot easier to survive in the biome. Once the diagonal strip has been located, the main thing to do is to find a good area to farm Souls of Night and Ichor, as the two will be needed for many recipes in the game. The best place would be a wide, open area with a little "safe zone" like an Underground Cabin where the player can take cover from enemies and heal. If no such place is found, with a couple Mining potions or Explosives it can be built.
There are many new enemies that will threaten the player: the Herpling, Floaty Gross, Ichor Sticker, Crimslime, Blood Jelly, Crimson Axe and very rarely the Crimson Mimic. Red Pigrons will also appear on an Underground Snow Biome infected by the Crimson.
- Herplings are very dangerous; they are fast, have a lot of knockback resistance and do a lot of 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.
- Floaty Grosses attack similarly to Wraiths by going through blocks. They also have a small chance to inflict the Weak debuff on hit. They don't have a lot of health, and they are very vulnerable to knockback, so they aren't too hard to deal with. However they can easily catch a player off guard with their ability to go through blocks. They are also more dangerous when dealing with multiple enemies at once.
- Ichor Stickers are arguably the most dangerous enemy. They have more health than the other enemies, and they shoot an accurate Ichor spit which does a lot of damage and inflicts the Ichor debuff, which will reduce defense by 20. They can't attack through blocks however, and their rather big size will get them stuck more frequently on blocks as well as making them easier to hit.
- Crimslimes and Blood Jellies act just like a regular Slime or Jellyfish, but with higher stats. They aren't very dangerous compared to the other enemies.
- Crimson Axes are an uncommon enemy that can phase through blocks, and can inflict Cursed on hit. While this status effect can be devastating, they will stop moving if attacked, so they are fairly easy to deal with.
- Crimson Mimics should be avoided at all costs, as they are much harder to kill than any other enemy found, Including the Brain of Cthulhu. You will need much better weapons and armor to deal with them.
- The central cave of the Crimson Chasms makes an excellent arena to kill the Brain of Cthulhu, once you've fitted it with platforms, Campfires, and other conveniences.
- To summon him in the arena, you can break more Crimson Hearts and dash for the arena, or just use a Bloody Spine to summon the Brain at your leisure.
- Even if you can't defeat the Brain outright, killing its Creepers will give you Tissue Samples and Crimtane Ore, eventually letting you make Crimson armor.