
With the arrival of Path of Exile 2 0.5.0, endgame league mechanics have changed quite a lot. One of the biggest updates is that each mechanic can now unlock all 30+ of its passive points. Once invested, these passives can provide solid returns, so it is worth finishing the setup for every mechanic you plan to farm.
This guide focuses on Delirium. It explains how to start the Delirium mechanic, complete the related task chain, and collect all Delirium passive points.
The Delirium progression can be divided into two parts. First, you need to trigger the Delirium questline in the Atlas. Then, you need to finish the task that unlocks the main Delirium progression.

While running Atlas maps, encounter Delirium content. During this process, you will meet The Elder Madox . This is the starting point of the Delirium questline.
After the first encounter, follow the quest guidance to Withered Willow. This area becomes the main hub for the Delirium task chain.

Once you arrive at Withered Willow, continue following the quest markers. The task will send you through several maps and encounters. According to the source notes, this section includes several boss fights, roughly four in total.

After completing the guided maps, you will meet the Elder Madox again. This advances the questline into the next stage, where the actual Delirium unlock task begins.
Follow the quest guidance to the Renly. In this area, you need to fight through seven waves of enemies. Clear all waves to complete the encounter.
After the seven waves are cleared, the quest item Raven's Reflection will drop. Pick it up before leaving the area.

Go back to Withered Willow. Interact with the mirror there and use Raven's Reflection to open the boss encounter.

Clear the boss fight opened by the mirror. After this, the core Delirium task is finished, and the Delirium system should be properly unlocked for further progression.
To obtain all Delirium passive points, continue clearing the maps related to Withered Willow. Once you finish the connected Withered Willow map sequence, you should be able to collect the full Delirium passive progression, up to all 31 points.