Thorium: An Awesome Terraria Mod


Thorium 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 want to spice up your gameplay a bit, just install Thorium mod, it almost double the content of the game.

Thorium 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 “Thorium mod” in the search bar. You can then install this mod with its dependencies.

14 new bosses

Thorium mod adds a lot of bosses. It adds 3 mini-bosses, 6 pre-hardmode bosses, and 5 hardmode bosses. Here is a list of some bosses:

  • Grand Thunder Bird: he’s the easiest boss added by the Thorium mod. it has the lowest damage and health of all bosses, even less than the King Slime. You can get some useful very early-game items such as a magic staff or a bow when you defeat him. To spawn him, you have to craft a Grand Flare Gun and use it with a Storm Flare as ammunition. It will only work if you’re in the Desert Biome and during the day. You can craft these things using Iron/Lead Bars, Talons, and Arcane Dust.
  • Viscount: he’s a pre-hardmode boss that must be fought underground. He drops bat and vampire items, such as the Vampire Scepter (a staff draining enemies’ life) or the Bat Wing (a yoyo releasing homing bat projectiles). He can be summoned using 5 Unholy Shards at a Blood Altar. You drop Unholy Shards on enemies during the Blood Moon, and you can find a Blood Altar in Blood Chambers (structures found underground).
  • Star Scouter: the Star Scouter is a pre-hardmode boss who can be considered specific to the Space Biome. By defeating him, you will get Star items such as the Hit Scanner (a gun transforming your munition into a beam traveling very quickly) or the Star Rod (a heal spell making stars fall from the sky to the cursor and healing allies they touch). To make it spawn, you have to craft a Star Caller using 10 Meteorite Bars and 1 Strange Alien Tech (you drop it from U.F.O encountered around meteorites). You have to use the Star Caller in the Space Biome to summon the Star Scouter.
  • Borean Strider: this is the easiest hardmode boss added by Thorium you can fight. It’s a Snow Biome-specific boss. Some useful items you can drop on this boss are the Glacier (a powerful sword) or the Freeze Ray (a gun shooting 3 bullets in succession, inflicting the Freezing debuff, causing enemies to move significantly slower). This boss spawns naturally in the Snow Biome during blizzards, but you can also make him spawn naturally using a Strider’s Tear in the Snow Biome, also during blizzards. You can drop this item on hardmode monsters living in the Snow Biome.
  • Forgotten One: it’s a post-Plantera boss found in the Aquatic Depths (a biome added by Thorium). You can drop an armor on this boss: the Whispering Armor. It’s an armor increasing radiant damage (new damage type added by Thorium) a lot, and also giving a lot of defense. You can make it spawn by killing 3 Aquatic Hallucinations found in the Aquatic Depths.
  • The Primordials: it’s the final Thorium boss. It’s a post-Moon Lors boss. You drop the very end-game crafting materials on them. You can summon them using the Doom Sayer’s Coin at night. It’s a consumable you can craft using fragments of each Lunar Events pillar.
Borean Strider Thorium mod
The Borean Strider

1 new biome

Thorium only adds 1 biome. But it adds tons of new things to other biomes as it adds new enemies, so also new loot, new weapons, new armor, etc…

The unique biome added by Thorium is called “The Aquatic Depths”. It’s an underground biome filled with water. You can find it underneath the Ocean’s sand, on the opposite side of the Dungeon. You can enter this biome from a huge hole in the sand. You find in this biome unique blocks, enemies, and items. There is also new music.

As this biome is completely underwater, it can be hard to explore it. That’s why you can find ambient objects releasing bubbles granting the Refreshing Bubble buff, allowing you to breathe underwater and to move at normal speed for a short duration. You can catch these bubbles from a bigger range if you hold the Bubble Magnet tool in your hand. You can find it in Water Chests.

The new ore added by this biome is the Aquaite. Combining it with other items in this biome such as Pearls will allow you to craft water-related stuff like the Tide Hunter or the Depth Diver sets.

While in the Aquatic Depths, you will be affected by a debuff making you lose health over time if you’re exposed to air. This debuff is removed once you have defeated the Forgotten One.

Thorium the Aquatic Depths

3 new classes

Thorium adds 2 new classes to the game and develops one existing class to make it more individual. This class is the Thrower Class.


There are already throwing weapons in Terraria. But these weapons don’t do some specific damage, and there is no Throwing Class in vanilla.

Thorium adds one and develops it with more than 100 items. It adds new mechanics:

  • Throwing damage: throwing weapons deal this type of damage. There are armors and accessories implemented in Thorium increasing throwing damage.
  • Technique Scrolls: these items can be used to grant the player special abilities. Using a Technique Scroll draws from the player’s Technique Points. They regenerate when the player deals throwing damage. For example, there is a technique allowing the player to teleport to the cursor’s location.
  • Thrower Exhaustion: this mechanic adds an exhaustion bar. It’s a bar filling up when the player uses a non-consumable throwing weapon. When the bar is complete, the player gets the Exhaustion debuff for 20 seconds, reducing throwing damage by 20% per use of a non-consumable throwing weapon.


The Healer Class is a new class added by Thorium. It aims to provide health to allies, functioning as a support. It makes this class useful mainly in multiplayer. But this class can also be played in single-player as there are some healer items dealing damage. This damage is called radiant damage. But keep in mind the main purpose of this class isn’t to deal damage but to heal and support allies.

This class also adds new mechanics to the game:

  • Soul Essence: damaging enemies with Scythes will provide some amount of Soul Essence. When the player has collected 5 stacks of Soul Essence, he will recover mana and health based on his healer stats.
  • Radiant Corruption: certain equipment can “corrupt your radiant powers”. It means your corrupted radiant weapons will begin to inflict either the Light Curse debuff dealing 8 damage per second to the target, or the Shadowflame debuff making enemies lose 15 health per second and preventing health regeneration.
  • Auras: auras are summoned using spells. They look like big rings around the player, granting effects to all the nearby allies.


The Bard is the second class added by Thorium. It focuses on providing short buffs while dealing symphonic damage. This class works better in multiplayer because the buffs can also affect allies standing nearby the Bard.

This class adds new mechanics to the game:

  • Inspiration: it’s a resource similar to mana used to make bard weapons work. It regenerates automatically. Some items, consumables, and equipment can improve the Inspiration-related stats.
  • Big Instruments: some bard weapons are called Big Instruments. They utilize a timing mechanic. You need to utilize the weapon while a marker is over a highlighted area to gain buffs and make the weapon more powerful.


Thorium mod adds some mechanics. We’ve already seen some of them above when talking about classes. It also modifies a lot of existing mechanics.

  • Crowd Control: these are new debuffs you can inflict on enemies. They allow you to slow enemies down, stun them, increase the damage they take, make airborne enemies fall, etc…
  • Death Prevention: when your health reaches 0 in vanilla, you instantly die. Thanks to this new mechanic, various items can prevent you from dying, delay your death, or revive you with some health.
  • Life Shield: some items allow you to temporarily increase your maximum health. You can get this additional health using weapons, tools, accessories, or armor.
  • Out of Combat: you’re considered out of combat when you have not damaged an enemy in the last 5 seconds. Some items work differently or have different effects when you’re in/out of combat.
  • Special Abilities: some armor and equipment can give special effects when you hit the “Special Ability” key. For example, the Celestial Armor allows you to create a healing aura around you when you hit the key. Some Special Abilities have a cooldown, meaning you have to wait a defined time before being able to use them again.
  • Transformations: certain items added by Thorium allow you to transform into creatures or enemies. You can’t use any item while you’re transformed, you can only use the abilities given by the transformation. For example, the Magma Charm allows you to transform into a kind of lava fish, making you immune to lava, reducing your fall damage, and making you able to fit into 1-block tall gaps.

In addition to these mechanics, there are those whose we talked about earlier and there are modifications to existing mechanics such as new Fish Rods or new items rarities.

10 new town NPCs

Thorium adds a lot of new NPCs. Most of them are special in the sense that they can do special actions. Some basic NPCs are the Blacksmith (although he can be very useful as it sells ores), the Diverman (he’s selling sea stuff such as Corals), or the Druid (he’s selling seeds which can be useful in the early game). The others are:

  • Desert Acolyte: sells desert-related stuff. He can trigger a sandstorm in the Desert for 1 Gold Coin. He comes into your world after the Grand Thunderbird has been defeated
  • Tracker: he hands out contracts to kill certain enemies. The items he sells depend on the contracts you’ve completed. He comes into your world after the Eye of Cthulhu has been defeated.
  • Weapon Master: an hardmode NPC selling some weapons. You can hire him for 10 Gold Coins. It will make a demon minion spawn, following you and attacking enemies. He comes into your world after the Fallen Beholder has been defeated.
  • Cobbler: this NPC sells boots and movement speed-related accessories. He can grant you a buff for free making you move faster and emitting some light when moving. He comes into your world if you have any boots in your inventory and if you also have an Aglet (HOW TO GET AN AGLET FAST IN TERRARIA (FULL GUIDE 2022)) and an Anklet of the Wind.
  • Confused Zombie: he sells zombie-related stuff. Every morning, he can sell you an Enemy Repellent (consumable making a kind of enemies passive for one day) at the cost of 1 Gold Coin. He comes into your world after Patch Werk (a mini-boss spawning during Blood Moon) has been defeated.
  • Cook: the cook sells you consumable items restoring health, mana, or granting buffs. You can give him Recipes to make him sell more powerful consumables. He comes into your world after King Slime has been defeated.
  • Spiritualist: he sells spirituality-related items. You can give him 5 Purified Shards to be granted a buff allowing you to respawn when you die, for 5 minutes. He comes into your world after Buried Champion has been defeated.

1 new structure

Thorium adds a unique structure: the Blood Chamber. It’s located within the Caverns and made of obsidian items. In the center of this structure, there is a Blood Altar, which is used to summon the Viscount. There is only one Blood Chamber per world.

Thorium Blood Chamber


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

For more information about Thorium mod, consider checking the Thorium Mod wiki. On the wiki, there is also a Boss Progression Guide. It’s something useful if you’re beginning with Thorium mod but not mandatory as Thorium follows the classic vanilla gameplay. 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: Thorium Mod Discord.

For more guides or tutorials, be sure to see our other articles as CRIMTANE BARS: TERRARIA ITEM GUIDE (2022) or ESSENTIAL BOSSES TO BEAT: TERRARIA GUIDE (2022).

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