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Crafting Basics: Fossils and Resonators

Last Updated: March 29th 2024

Necropolis 3.24

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Introduced with Delve League in 3.17, Fossils and Resonators are currency which offer a reasonably deterministic way to craft via targeted reforging and other complex options such as mod-blocking.

The main currency used with Fossil Crafting are:

  • Fossils (e.g. Frigid Fossil)
  • Primitive Chaotic Resonator
  • Potent Chaotic Resonator
  • Prime Chaotic Resonator


Fossils are a special crafting currency that can be socketed into Resonators to enable targeted tag-based reforging.

  • They are commonly used for targeting modifiers with specific tags. (e.g. +# to Maximum Life and Regenerate # Life per second are Life modifiers.)
  • For example, when socketing a Pristine Fossil into a Primitive Chaotic Resonator it reforges a Rare item, increasing the odds of rolling Life tags by 10x while blocking any modifiers with a Defence tag.
  • In advanced cases, Fossils are used to massively increase the chance of hitting extremely low-weight modifiers like +1 to Level of all Spell Skill Gems on a Wand by blocking nearly every other modifier from being rolled through a 4 Fossil combination socketed in a Prime Chaotic Resonator.


In order to use Fossils they must first be placed inside a Resonator, which can only be used on Rare items. For example, a Primitive Chaotic Resonator only needs 1 Fossil socketed while Potent Chaotic Resonators and higher require 2+.

The 4 types of Resonators are:

  • Primitive Chaotic Resonator
  • Potent Chaotic Resonator
  • Powerful Chaotic Resonator
  • Prime Chaotic Resonator

Higher Fossil count combinations drastically modify crafting outcomes and enable complex methods of determinism through mod-targeting and blocking. For example, high-end crafts like Minion Wands make use of four-socket Resonators to not only target mods but also block others from rolling.

Using Craft of Exile for Fossil Crafting

The Craft of Exile calculator is the by far the most useful tool for Fossil crafting since combining Fossils results in varying crafting chances.

Starting Off

After loading the Craft of Exile front page, click the Calculator tab to navigate to the the base selection menu.

Choose Your Base

After selecting your Base Group, you are met with options to configure Item Level, Item Base and Influence. In this case an intelligence based helmet with no Influence is selected. Match these settings to the exact item you are making.

Choose Your Desired Mods

In this case, #% increased Energy Shield and +# to maximum Energy Shield are the mods chosen for a Hubris Circlet for Energy Shield builds.

Running the Calculator

Select Fossils

After choosing your desired modifiers, select "Fossils" for the method.

Compute Best Selection

After, click the compute best selection button. Make sure your desired modifiers are under the item requirements.


Once the calculation is done, you are presented with a cost efficiency breakdown and optimal Fossil combinations. In this case, a single Dense Fossils is the best option.

If the cost breakdown is unrealistically expensive, this is probably a sign that fossil crafting is not a good way to craft your item.

Example 1: Hunter-Influenced Stygian Vise

A common use for Fossil crafting is crafting Influenced items.

  • One of the most common Belt crafts is a Hunter Stygian Vise with high Life modifiers such as +(90-99) to maximum Life and the Hunter specific (7-10)% increased maximum Life available at item level 84+.
  • A Stygian Vise base is desired since it allows the use of an Abyss Jewel.

The process proceeds as follows:

  • A Hunter's Exalted Orb is first used on a Rare Stygian Vise ilvl 84+. This is usually cheaper than buying the base already made.
  • Pristine Fossil paired with Primitive Chaotic Resonator is the best way to target our desired Life modifiers. They apply a 10x multiplier to both while also blocking high-weight Defence modifiers such as +# to Armour and +# to maximum Energy Shield.
  • It's recommended to use 4 Fertile Catalysts on the belt while it is white, before continuing for a cheap way to increase the value of Life modifiers.
The Craft of Exile calculator shows a 1/92 chance of success per Fossil/Resonator combo.

Once the Prefixes are acquired, the process for Suffixes follows:

Step 1

High-Life Hunter

Assuming Prefixes are full, the most common approach to Suffixes is through Benchcrafting Prefixes Cannot Be Changed and using a Veiled Chaos Orb.

Step 2

High-Life, Hunter

If your Suffixes aren't filled afterward, Benchcraft +# to Strength and Dexterity or #% increased Cooldown Recovery Rate to block high-weighted unveils before going to Jun.

Step 3

High-Life, Hunter

Most likely Jun will offer good unveils like +(16-20)% to Cold and Chaos Resistance or +(16-20)% to Fire and Chaos Resistance. If she doesn't, lock the Prefixes with Prefixes Cannot be Changed and try again with another Veiled Chaos Orb.

Step 4

High-Life, Hunter

If you have 2 open Suffixes, Benchcraft a high-weighted modifier such as +# to Strength (or keep the hybrid benchcraft from the example) and use an Exalted Orb.

Step 5

High-Life, Hunter

Here resistance was slammed with an Exalted Orb which is ideal.

Because the cost to get back to this point is so high, it's not worth it to remake your Suffixes if you hit something useless like #% reduced Enemy Stun Threshold.

Step 6

High-Life, Hunter

If you have an open Suffix after the previous step or if your Veiled Chaos Orb reforged into 2 Suffixes, you can finish with a Benchcraft.

In this case aim for solid Resistances to pair with your high-tier Life modifiers.

Example 2: +2 Convoking Wand for Minion Builds

One of the more advanced uses for Fossils is crafting +2 Minion Wands

  • This craft uses Prime Chaotic Resonators to target 2 low-weight modifiers: +1 to Level of all Minion Skill Gems, and +1 to level of all Spell Skill Gems by blocking most other modifiers using a 4 fossil combination.
  • Your Prime Chaotic Resonator will be socketed with: Corroded Fossil, Jagged Fossil, Shuddering Fossil, and Metallic Fossil.
  • A Convoking Wand with an Item Level of 84+ is used since it enables the highest tier of Minions deal #% increased Damage to be hit.
With both desired prefixes selected, it's a 1/12 chance on average to hit the highest tier of Minions deal #% increased Damage.

Fractured +1 Spell Skill Gem Base

Fractured +1 Spell

To make a perfect, triple tier 1 Prefix wand, a Fractured base is usually used unless an influenced Suffix is desired.

High-Budget Minion Wand


After an expensive process utilizing Prefix locks and Veiled Crafting for Suffixes, this is the usual end result for a high-budget minion wand.


  • Fossils and Resonators offer a reasonably deterministic way to craft via targeted reforging and other complex options such as mod-blocking.
  • Whether it's a single-socket Resonator craft like a Hunter Stygian Vise, or a complex end-game item such as a +2 Convoking Wand, Fossils are useful throughout all levels of crafting in Path of Exile.
  • There are four types of Resonators. a Primitive Chaotic Resonator only needs 1 Fossil socketed while Potent Chaotic Resonators and higher require 2+.
  • Craft of Exile is a vital tool for calculating averages for all avenues of Fossil crafting.


Written by spicysushi
Reviewed by Facefoot, Tripolarbear

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