Core Nodes for Fractured Essence:

Increased Chance for Fracturing Mirrors to Spawn: These nodes enhance the chances of finding Fracturing Mirrors during your Delirium runs, maximizing your chances to Path of exile currency face powerful bosses.
Increased Boss Loot Quality: These nodes enhance the quality of loot dropped by Fracturing Mirror bosses, increasing the chances of acquiring valuable and rare items.
Boss Damage and Health Buffs: Some nodes may increase the damage or health of Delirium bosses, allowing you to fight stronger enemies for better rewards.
Supporting Nodes:

Increased Movement Speed: Since you’ll be exploring the Delirium fog and dealing with a large number of enemies, increased movement speed helps you navigate the fog and activate the Fracturing Mirrors more efficiently.
Increased Damage: Fracturing Essence relies on summoning strong bosses, and you’ll need to buy POE2 Currency ensure that your damage output is sufficient to defeat them.
Optional Path for Survivability:

Increased Life Regen or Damage Mitigation: Since Delirium encounters can be brutal, you might also want to invest in nodes that provide defensive buffs to survive longer in the fog and during boss fights.
Faster Recovery or Life Leech: These nodes will keep your health topped up as you face tougher and more numerous enemies.
Conclusion:
Fractured Essence is a powerful mechanic in Delirium encounters that can greatly enhance both the challenge and rewards of your endgame activities. By summoning stronger Delirium bosses with better loot and unique drops, it provides a strategic way to maximize your Delirium progression and loot acquisition.

Focusing on Fractured Essence in your passive skill tree and during your encounters will ensure that you face higher-tier bosses, gain valuable rewards, and potentially unlock Simulacrum encounters for even greater loot and challenges. The risk is high, but the reward is definitely worth it for those who are up for the challenge!