Synthesis League Guide - Path of Exile Resource Guide - (2024)


Welcome to our Synthesis Guide, Exile! This League Mechanic was introduced in Patch 3.6.0 (March 2019) and brought both Fractured Items and Synthesised Items to the game, which are still important today. It also introduced 5 new endgame bosses: Distant Memories (Augmented / Altered / Rewritten / Twisted Distant Memory) and Cortex, which is part of Maven's Invitation (Maven's Invitation: The Feared) and has an Uber version.

The theme of the League was about the forgotten memories of High Templar Venarius, who didn't recognise himself anymore. Map encounters teleported you into a collapsing memory that you had to clear before it fully faded (similar to an Incursion encounter with a shrinking area), which you could then use as a building block in the High Templar's Memory Nexus. This enabled you to create what was essentially a separate mini-Atlas of Maps to run. Inside, Venarius would offer you the ability to create new item bases by combining similar items in the Synthesiser.

After the League, ended both the Memory Nexus and the Synthesiser were discontinued. What remains today are the boss encounters, their unique item drops and Fractured/Synthesised items that can be acquired from various sources. Some Synthesised Items have incredibly powerful implicit modifiers that are best-in-slot for certain builds and can be extremely valuable in Trade Leagues because they are so difficult to find.

Fractured Items

Synthesis League Guide - Path of Exile Resource Guide - (1)

Fractured Items nowadays can drop randomly from certain League Mechanics such as Delve or appear in reward choices from Rituals.

Fractured Items are exactly like any other magic or rare item, but with one affix being completely locked in place. This Fractured mod can't be removed or changed in any way, such as using a Chaos Orb, Divine Orb or Vaal Orb (even bricking the item with a failed Corruption keeps the Fractured mod). These items can be identified by their light blue glow and the Synthesis influence icons next to the name. The Fractured mod itself is always at the top of the explicit affix list.

Fractured Items can never become normal (white) quality, as there's always at least one mod on them. This prevents certain crafting methods that require normal quality items from being used on them, such as Tiny's Trial in a Syndicate Safehouse. Fractured Items cannot be influenced by the Conquerors/Shaper/Elder, or be upgraded into unique quality (using Orb of Chance). However, Fractured Items with a great Fractured mod may be an amazing crafting base to get started for e.g. Essence spamming or Harvest rerolls.

Speaking of Harvest: Wild Patches can very rarely offer a craft from a Tier 4 Boss Seed (Wild Thornfruit) that allows you to fracture a random mod on an item of choice. The three possible outcomes of this particular Seed are:

  • Fracture a random modifier on an item with at least 5 modifiers, locking it in place.
  • Fracture a random Prefix on an item with at least 3 Prefixes.
  • Fracture a random Suffix on an item with at least 3 Suffixes.

All three of them have the same limitation: They can't be used on Influenced, Synthesised or Fractured items.

Synthesised Items

Synthesised Items are special bases that have new, typically unobtainable implicit modifiers (up to 3 at a time). The full list and their ranges are massive (check them for each base type here). They are not necessarily better than regular items - in fact, in some cases these implicits can even be a direct downgrade from the standard implicits of some bases. Synthesised Items have a distinct blue glow and cannot be upgraded into unique quality using an Orb of Chance because their new base types don't have any valid uniques.

There is no way to reliably target-farm a desired Synthesised base anymore. You have to rely on the law of large numbers and hope to hit the jackpot. The main sources of Synthesised Items are the Synthesised Maps (with the Atlas Passives allocated) and their corresponding Maven Invitations.

Here are some noteworthy high-end implicit modifiers that can be found on Synthesised Items:

  • Bows/Quivers: Bow Attacks fire an additional Arrow
  • Belts: +13-15% increased Strength/Dexterity/Intelligence
  • Rings: Curse Enemies with Conductivity/Elemental Weakness/Flammability/Frostbite/Vulnerability on Hit, with 20% increased Effect
  • Boots: Onslaught
  • Body Armours: 10% chance to gain a Frenzy Charge on Hit
  • Body Armours: 15% chance to gain a Power Charge on Critical Strike
  • Body Armours: Gain 1 Endurance Charge every second if you've been Hit Recently
  • Shields: +2% to all maximum Resistances
  • Shields: Immune to Curses if Corrupted

Synthesised Unique Items

The Synthesis Bosses (see below) each drop special Unique Items which come with Synthesised Implicits. With the Atlas Passives allocated, they can have up to three implicits, potentially making them a lot more powerful.

Drops from Synthetes

  • Circle of Anguish
  • Circle of Fear
  • Circle of Guilt
  • Circle of Nostalgia
  • Circle of Regret
  • Mask of the Tribunal
  • Perepiteia
  • Storm's Gift

Drops from Cortex

  • Bottled Faith (has no Synthesis Implicits)
  • Garb of the Ephemeral
  • Nebulis
  • Offering to the Serpent

Synthesis Maps

There are a total of 5 unique Synthesised Maps, each of which holds one special boss encounter at the end. They are always Corrupted and come with additional random Map and Synthesis modifiers. Synthesised Maps are always unique.

Each of them rolls with the following mods:

  • 25% increased Pack size
  • 100% increased Experience gain
  • Monster Level: 80 (Cortex: 83)
  • Map has (3-5) additional random Modifiers
  • Map has (2-4) additional Synthesis Global Modifiers

Due to the extra random Map modifiers, the boss encounters can vary greatly in difficulty, depending on how it rolled and how well your build handles them. The Synthesis modifiers increase rewards such as adding extra loot to defeated monsters by giving them a chance to drop Fossils, Breach Splinters, Currency, ... (click here for a full list). With the right Atlas Passives allocated, these Maps are also by far the best source of Synthesised Items.

The main way of acquiring Synthesis Maps is through Atlas Passives by giving defeated Map Bosses a higher chance to drop them. They can also rarely appear in Kirac Missions or as a reward from certain League Mechanics (Tujen's inventory, Ritual). Justified Ambition is a Divination Card that drops from Conquerors. Synthesised Maps are not part of the Atlas and don't grant completion bonuses on their own, but are part of Maven's Invitations that do.

Synthesis Bosses

Here is a concise overview of the 5 Synthesis Boss encounters. The Synthetes are way easier than Cortex, which is higher level and has a longer fight with multiple phases. Cortex also has a harder Replica version and an even harder Uber version.

Altered Synthete

Augmented Synthete

Rewritten Synthete

Twisted Synthete


Synthesis League Guide - Path of Exile Resource Guide - (7) Altered Synthete

  • Siege Map tile set

Boss Abilities

  • Auto-attack deals Cold Damage and inflicts Chill
  • Frontal Sweep
  • Spawns temporary Void Zones
  • Side-ways Barrage
  • Three-way Creeping Frost AoE
  • Covers a large frontal area in Frost Tiles which explode after short delay
  • Shield + Add Spawns
  • Outer circle fills up with Frost Cannons as fight progresses, shooting projectiles
  • Below 50%: All active Frost Cannons fire massive projectiles towards the boss regularly
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Synthesis League Guide - Path of Exile Resource Guide - (9) Augmented Synthete

  • Torched Courts tile set
  • Movement skills like Flame Dash help greatly to navigate around the map as it's full of impassable terrain

Boss Abilities

  • Auto-attack dashes towards target, deals Fire Damage
  • Spawns temporary Void Zones
  • Shield + Add Spawns
  • Jump + Slam Dunk
  • Forward Slam + Massive Beam Shot combo
  • Outer circle fills up with Fire Cannons that regularly appear and fire 5 times as fight progresses
  • Below 50%: Spreads Fire Mines in all directions, which explode after a short delay
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Synthesis League Guide - Path of Exile Resource Guide - (11) Rewritten Synthete

  • Basilica Map tile set

Boss Abilities

  • Has a soft enrage by filling up the Arena with Floating Mines that activate when you step on them and explode the next time you approach. These don't despawn and can re-trigger infinitely.
  • Auto-attacks slam the ground in a circular AoE
  • Spawns temporary Void Zones
  • Jump + Slam Dunk
  • V-shaped frontal line AoE
  • Massive channeled Beam towards the player's position
  • Regular Add Spawns
  • Below 50%: Spins clockwise, then counter-clockwise, releasing Void Orbs from both arms in all directions
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Synthesis League Guide - Path of Exile Resource Guide - (13) Twisted Synthete

  • Park Map tile set

Boss Abilities

  • Auto-attacks fire Void Ball Lightnings
  • Spawns Void Zones
  • Shield + Add Spawns
  • Multiple versions of a Multi-Projectile attack that target the player's location, then sends piercing Lightning Projectiles back towards the boss
    • Frontal Triple-Shot
    • Empowered Frontal Barrage
    • Cross-Shot (in front, behind, to the left, to the right of the boss)
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  • Stepping into the outer circle activates a dormant Lightning Cannon which can fire the same Lightning Projectiles through the entire Arena
  • Below 50%: Spins clockwise twice, extending Lightning Beams from both arms that Shock and reduce Action Speed
  • Below 50%: Channels a Beam which jumps from one Lightning Cannon to any other random Cannon until all of them are charged, then releases a Beam Shot covering all connections between them.

Synthesis League Guide - Path of Exile Resource Guide - (15) Cortex

  • Laboratory Map tile set
  • The fight has 5 phases: 2x bosses, 1x add spawn, 2x bosses again
  • Most of the boss abilities are similar to the Synthetes, but some new ones are added
  • This fight is much more difficult and longer than the Synthete encounters
  • Void Zones appear during the fight, which are cleared after each phase
  • Only the last boss (Synthete Nightmare) is present in Maven's Invitation: The Feared
  • Full-clearing the Map is recommended for valuable loot and high level Synthesised Items (with Atlas Passives allocated)
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Phase 1 - Fractal Gargantuan

  • Similar to the Augmented Synthete
  • Double Frontal Sweep
  • Throws Orbs and detonates them with a Beam in various ways:
    • Single frontal Orb
    • Frontal Sweep Barrage from one arm, then detonate with a Beam Sweep from the other
    • Spin with Orbs releasing from both arms, then second Spin with Beams from both arms to detonate

Phase 2 - Synthete Masterpiece

  • Similar to the Altered Synthete
  • Auto-attacks Chill (30%) and release three overlapping Projectiles
  • Frontal parallel Laser Barrage
  • Focuses multiple Beams on the player's location, which explode in an AoE after a short delay
  • Massive charged up circular AoE focused on the player's location
  • Fires a Beam at the player's location, releasing four more Beams in all directions, which then spawn circling Orbs that deal damage on impact
  • Spawns accelerating Void Orbs that follow the player while charging up a massive Frontal Slam. The Orbs slow down the player to a crawl, then teleport you right in front of the boss, who immediately releases the charged up Slam. The only way to avoid the Slam is by using a Movement skill away from the cone-shaped AoE

Phase 3 - Add Phase

  • Four Portals appear that spawn various Synthesised Monsters
  • Lasts approximately half a minute

Phase 4 - Fractal Titan

  • Empowered version of Phase 1
  • Spawns Floating Mines from the Augmented Synthete encounter
  • Below 50%: Pulls in Floating Orbs from all directions that explode on contact, then charges up a massive circular AoE that covers most of the Arena

Phase 5 - Synthete Nightmare

  • Empowered version of Phase 2
  • Spawns Orbs in a circle around the Arena, then sends them towards the player's location
  • Chain teleports around the Arena, releasing Projectiles towards the player
  • Below 50: Channels Spiraling Beams that slowly close in on the bosses' location, then releases a massive circular AoE

Replica Version
This Map has a Replica version (found in Curio Displays in Heist) with the following mods:

  • 25% increased Pack size
  • 200% increased Experience gain
  • Monster Level: 84
  • Map has (6-8) additional random Modifiers
  • Map has (4-6) additional Synthesis Global Modifiers

Uber Version

Allocating Memento Mori enables the Uber Cortex encounter. This is an empowered version with massively increased Life & Damage and each boss phase spawns an additional Synthete boss. These do not despawn when a phase ends (except upon defeating the final boss) and should be dealt with first.

Atlas Passive Tree

Synthesis has one wheel with various Passives located at the very top left of the Atlas Passive Tree. If you are interested in farming Synthesis content, these are a must-have.

Small Passives

Synthesis Monster Pack Size (x7)

  • 4% increased Synthesised Monster Pack size


  • Synaptic Impulses
    • +0.5% chance for a Synthesis Map to drop from Map Bosses (Tier 11+)
    • Synthesised Unique Items dropped in Areas have 3 Synthesised Implicit Modifiers
  • Vivid Memories
    • +0.5% chance for a Synthesis Map to drop from Map Bosses (Tier 11+)
    • 100% increased effect of Additional Modifiers on Unique Synthesis Maps
  • Neural Pathways
    • +0.5% chance for a Synthesis Map to drop from Map Bosses (Tier 11+)
    • Monsters in Synthesis Maps have 2% chance to drop Synthesised Items

Uber Cortex

  • Memento Mori
    • The Cortex is level 85
    • Venarius' full power is unleashed in the Cortex
    • Venarius drops 3 additional Rare Items with 3 less common Synthesised Implicit Modifiers


  • Synthesis is part of the Endgame of PoE, adding special unique Maps with boss encounters, as well as playing a part in two different Maven's Invitations.
  • Fractured Items have one mod that cannot be changed by any means, making them a great crafting base by guaranteeing a specific result every single time.
  • Synthesised Items are a lottery and are mostly acquired by farming Synthesised Maps with the Atlas Passives allocated. They have their own set implicits, some of which are best-in-slot for many builds.


Written by wudijo.
Reviewed by Enki, MacroBioBoi & Chewingnom.

Synthesis League Guide - Path of Exile Resource Guide - (2024)


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