Calamity Mod: One of the Best Terraria Mods


Calamity mod is one of the largest Terraria mods, and also one of the most popular. It adds tons of content including new mechanics, new bosses, new biomes, new enemies, new structures, a lot of items, etc... If you've finished Terraria multiple times and you think you are an expert, just install Calamity mod, you will discover a whole new game as it not just double the content of the game, but it also significantly increases difficulty.

Calamity mod installation

The first step to getting started with this mod is to install it. You can do it easily through tModLoader. Just go to “Download Mods” and type “Calamity mod” in the search bar. You can then install this mod with its dependencies.

40 new bosses

Yes, this number is amazing. Calamity mod adds a lot of new bosses. It adds 12 mini-bosses, 5 pre-hardmode bosses, 9 hardmode bosses, 13 post-Moon Lord bosses, and 1 super boss. Here is a list of some bosses:

  • Desert Scourge: this one is the easiest boss added by Calamity mod. It is intended to be fought after King Slime and before the Eye of Cthulhu. You can drop useful items such as the Seabound Staff which is one of the first summoning weapons you can get in the game. It summons a starfish-like minion. To summon this boss, you need a Desert Medallion which is an item you can craft using materials found in the Desert.
  • The Slime God: it is the hardest pre-hardmode boss added by Calamity mod. The boss is comprised of three main parts, the Crimulan Slime God, the Ebonian Slime God, and the Core itself. You can make it spawn using an Overloaded Sludge which requires you to farm some slimes added by the Calamity mod to get the crafting materials. This boss drops the Mana Polarizer which is one of the best accessories to enter hardmode.
  • Cryogen: the first hardmode boss added by Calamity mod you’re supposed to fight. You can spawn it using a Cryo Key you can get using some Souls of Night and some Souls of Light, and also some materials found in the Snow Biome. You can drop a lot of good items on him, and also defeating him makes Cryonic Ores spawn in the Ice Biome where he was defeated. These ores can be used to craft Cryonic Bars, unlocking you a new armor and tons of new items.
  • Astrum Deus: it’s a hardmode boss. When you begin the fight against it, he looks like the Destroyer but it splits later in the fight. Defeating it is required to be able to mine Astral Ores, used for Astral Bars, one of the most advanced bars you can get pre-Moon Lord. You can drop on this boss things such as The Microwave, a powerful yoyo.
  • Jungle Dragon, Yharon: this one is a major post-Moon Lord boss, fought in the Jungle. It’s one of the most emblematic Calamity mod bosses. He’s incredibly challenging. Defeating him will give you access to the Auric Ores, unlocking one of the highest tiers of equipment in the game. He also drops some very powerful weapons.
  • Supreme Calamitas: also one of the major bosses in Calamity mod. It is one of the most challenging bosses in the game. Defeating this boss will grant you access to the Enchantment mechanic (we’ll talk about it later).
  • Adult Eidolon Wyrm: this is currently the only super boss in Calamity mod. Super bosses are bosses with immense health, defense, and damage (this super boss has 2 100 000 health in normal difficulty for example). Defeating this super boss unlocks very endgame items.
Terraria Calamity mod Boss
The Adult Eidolon Wyrm, isn’t he scary?

5 new biomes

Calamity mod adds 5 new biomes including their structures and enemies. But it also modifies some of the already existing biomes because it adds new enemies, structures, etc…

Sulphurous sea

It’s a biome replacing the Ocean on the Dungeon side of the world. It is composed of Sulphurous Sand. Sometimes, bubbles can spawn above Sulphurous Sand, inflicting the Poisoned debuff if they hit the player.

After the Eye of Cthulhu has been defeated, Acid Rain can occur in this biome. This is an event making new enemies spawn. You can get good drops helping you in pre-hardmode thanks to this event.


This biome is located just under the Sulphurous Sea. Indeed, there is a hole in the Sulphurous Sea allowing you to go directly deep into the Abyss.

This biome is divided into multiple layers. The deeper you go into the Abyss, the more dangerous it becomes. The two last layers are supposed to be explored, post-Moon Lord.

Astral infection

Upon defeating the Wall of Flesh, this biome will spawn in the world on the Dungeon side. It looks like a meteorite. Like Corruption, Crimson or Jungle, this biome will infect the nearby terrain and try to extend. You’re informed this spawn has spawned when you see the following message appearing on your screen: “A star has fallen from the heavens!”.

The meteor is made of Astral Ores, which you can only mine after defeating the boss Astrum Deus. This biome transforms the terrain into astral, Dirt becomes Astral Dirt, Stone becomes Astral Stone, etc…

Brimstone Crag

This biome is located on the right side of the Underworld. It is composed of Brimstone Slags and Charred Ores.

Lava is deadly in this biome because touching it won’t inflict the classic Lava debuff, but it will inflict the Searing Lava debuff, making you quickly lose your health. You can’t use lava immunity items such as the Lava Charm to be protected from this debuff.

Sunken Sea

The Sunken Sea is an aquatic biome you can find underneath the Underground Desert. It is composed of a series of caves filled with water. This biome is illuminated by glowing blue Prism Shards.

Most of the creatures you find in this biome are peaceful until provoked. This biome is more useful in hardmode than in pre-hardmode. Enemies also receive new abilities and drop new things in hardmode, making the exploration of this biome harder.

Terraria Calamity mod Biomes

1 new class

This one is a big one as it is not anything to add a class to the existing classes in Terraria. The class added by Calamity mod is the Rogue class. This class is largely developed in Calamity because there are a lot of weapons, accessories, armor sets, etc… for it.

Playing with the Rogue class grants you a new mechanic: Stealth.


When playing Rogue, if you don’t use any weapon for some time, you will gain Stealth. For each point of Stealth, you become a little more invisible (enemies are less likely to see you) and you gain +0.5% Rogue damage.

When Stealth is full, you can do a Stealth Strike, dealing a lot of damage around your target but consuming all your Stealth. Stealth is initially recovered in 3 or 9 seconds depending on your max Stealth.

Throwing class compatibility

Because Rogue damage is internally throwing damage, the Rogue class and the Throwing class are compatible. But it only works in one way:

  • Increased throwing damage will increase Rogue damage.
  • Increased Rogue damage won’t increase throwing damage.


We can’t give a number to the mechanics added by the Calamity mod, as it adds some mechanics, but also modifies a lot some of the already existing mechanics.

  • Aggro: it determines the distance at which enemies will attack the player. In vanilla, as soon as an enemy is on your screen, he will attack you, but thanks to aggro enemies will only attack you if you are too close to them.
  • Boss Rush: it’s a special event that will summon all the vanilla and Calamity mod bosses sequentially and in a predetermined order. The bosses spawn with increased health and damage. It’s recommended to try this event after all bosses have been defeated. You get nothing for defeating this event except a little trophy, it’s purely for challenge.
  • Revengeance Mode/Death Mode/Malice Mode: Calamity mod adds these three difficulty modes. Revengeance is harder than expert. It increases enemies’ spawn rate, enemies and bosses AI, and it also adds two mechanics, Rage Meter and Adrenaline Meter. Death Mode is more difficult than Revengeance Mode. It boosts enemies’ and bosses’ health, and damage, and allows bosses to spawn randomly. Malice is the hardest difficulty. It gives every boss a new AI.
  • Death Prevention: some items in the Calamity mod prevent death if the player takes fatal damage. It makes the player respawn with a certain amount of health.
  • Enchantment: it’s a mechanic unlocked in the very endgame. It allows you to apply new qualities to items. Each enchantment has an upside and a downside. For example, the “Aflame” enchantment allows your weapons to inflict a new debuff on enemies but it makes you lose health while you’re holding the weapon enchanted in your hand.
  • Proficiency: proficiency is a series of five attributes (one for each damage class) scaling in the game as the player progress. When you hit enemies, you gain proficiency for the damage type you hit the enemies with. The more proficiency you have for one damage type, the more your damage, speed, crit rate, etc… are increased.

In addition to these new mechanics, Calamity mod modifies existing mechanics such as fishing, debuffs, music in the game, etc…

5 new town NPCs

Calamity adds some new NPCs to the game:

  • Sea King: the Sea King is an NPC selling you some weapons or useful items such as Truffle Worms once Duke Fishron has been defeated. He can also grant you a unique buff allowing you to breathe underwater for 10 minutes or until you get hit. He can spawn after the Desert Scourge has been defeated.
  • Bandit: the Bandit is an NPC selling you Rogue-related weapons, accessories, and potions. He spawns after Skeletron has been defeated and if you have at least one Platinum Coin somewhere.
  • Drunk Princess: she sells you alcohol granting you buffs depending on your progression. She can also count the number of times you died in the world.
  • Archmage: he can spawn after Cryogen has been defeated and sells you ice-related items.
  • Brimstone Witch: she spawns after Supreme Calamitas has been defeated and can enchant your weapons.

5 new structures

Just like the Calamity mod adds new biomes, this mod also adds new structures:

  • Evil Island: an Evil Island is a unique sky island containing content of the opposite Evil Biome not present in your world. If your world is a Corruption Biome, the Evil Island will be Crimson for example. It contains blocks, ores, and a Biome Chest similar to those found in the Dungeon.
  • Shrines: Calamity mod adds new types of shrines to your world such as Corruption Shrines, Ice Shrines, Mushroom Shrines…
  • Arsenal Labs: these are abandoned research facilities generated in the Cavern layer. They contain various loots and are useful because you find in those things required to charge some weapons.
  • Planetoids: planetoids are like small planets you may find in the Space layer. There are many variants of Planetoids providing various loots.
Calamity mod Planetoid example

Tons of new items and enemies

There are tons of new items and enemies added to the game by the Calamity mod. Each new biome has its corresponding enemies, each new boss has a lot of corresponding items, there are new items related to the new game mechanics, etc… The list is huge.

For more information about Calamity mod, consider checking the Calamity Mod wiki. On the wiki, there is also a Mod Progression Guide. It’s something very useful if you’re beginning with Calamity mod, as there are so many things in this mod you can be completely lost with the number of bosses, items, etc… You can also find Class Setups on the wiki. There is also a Discord server where you can talk about this mod and find tips: Calamity Mod Discord.

For more guides or tutorials, be sure to see our other articles as NECRO ARMOR: THE BEST PRE-HARDMODE RANGE ARMOR or A COMPREHENSIVE GUIDE TO ALL THE COINS IN TERRARIA.

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