How to Use the Alchemical Reaction Chamber & Craft Weak Blood Shards in Blood Magic

If you’re working your way through Blood Magic and need to upgrade your Tier 3 Blood Altar to a Tier 4, you’re going to need a Weak Blood Shard — and to get one, you’ll need to master the Alchemical Reaction Chamber. In this guide, we’ll walk you through exactly how to build and use this multiblock machine, including a handy terracotta-to-clay trick and the full step-by-step process for crafting your first Weak Blood Shard.

What Is the Alchemical Reaction Chamber?

The Alchemical Reaction Chamber is a crafting machine built using Imbued Slates — your Tier 3 slates. Place it down in your workspace. At first glance the interface looks a little confusing, but once you understand how the slots work, it becomes a very powerful tool.

Cells You Can Use in the Alchemical Reaction Chamber

The Alchemical Reaction Chamber uses different cells to determine what kind of reaction takes place. The cells currently available include:

Primitive Hydration Cell

Reinforced Explosive Cell

Hell Forged Explosive Cell

Primitive Fuel Cell

You can browse the available recipes directly inside the chamber’s interface to see what each cell can produce.

Using the Chamber Like a Furnace: Terracotta to Clay

The Alchemical Reaction Chamber can also function similarly to a furnace. A great early use-case is quickly converting Terracotta into Clay. Here’s how to do it:

Step 1 — Insert Your Cell

Place your Primitive Hydration Cell into the dedicated cell slot on the left side of the interface.

Step 2 — Add Water

Place a Water Bucket into the fluid input slot at the top of the interface. This will fill the chamber with water, ready for the hydration reaction.

Step 3 — Add Terracotta and Collect Output

Place your Terracotta into the input slot. The chamber will begin crafting immediately. Your converted Clay — along with any liquid outputs — will appear in the output slots on the right-hand side of the interface.

Crafting a Weak Blood Shard

The main reason you’re here — crafting a Weak Blood Shard. This is a critical component required to upgrade your Blood Altar from Tier 3 to Tier 4. You will need two special ingredients for this recipe.

Ingredient 1 — Saturated Towel

To obtain a Saturated Towel, you’ll first need to complete the Hidden Realm Ritual. Once inside, locate some Towel, plant it, and then allow mobs to stand on top of it as it grows. Mobs standing on the growing Towel will gradually convert it into Saturated Towel.

Ingredient 2 — Sanguine Reverta

The Sanguine Reverta is crafted inside the Hellfire Forge. Note that while a Master Blood Orb can also be used, that is a higher-tier item. To craft the Sanguine Reverta you will need:

1x Imbued Slate

Shears

Stone

1x Iron Ingot

1x Tartaric Gem (charged with Demon Will)

Assembling the Recipe in the Chamber

With both ingredients ready, head to your Alchemical Reaction Chamber:

Place the Sanguine Reverta into the left input slot.

Place the Saturated Towel into the top input slot.

No water or additional fluid is required for this recipe.

The chamber will begin processing immediately. Once complete, collect your brand new Weak Blood Shard from the output slot on the right.

What Else Can the Alchemical Reaction Chamber Do?

The Weak Blood Shard is just the beginning. The Alchemical Reaction Chamber supports a wide variety of recipes depending on which cell you use and which fluids you feed into it. As you progress through Blood Magic, experimenting with the Reinforced Explosive Cell, Hell Forged Explosive Cell, and Primitive Fuel Cell will unlock even more powerful crafting options.

Summary

To recap: build your Alchemical Reaction Chamber using Imbued Slates, get comfortable with using different cells and fluid inputs, and then craft your Weak Blood Shard using a Sanguine Reverta (from the Hellfire Forge) and a Saturated Towel (grown with mobs via the Hidden Realm Ritual). With your Weak Blood Shard in hand, you’re one step closer to upgrading your Blood Altar to Tier 4.

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