[Updated on August 26, 2024, to revise outdated formatting and improve readability.]
After completing the quest Storming the Gates, it’s time to work on The Cost of Knowledge quest in Diablo 4. Beginning where you left off in Storming the Gates, you can continue into The Cost of Knowledge. This is primarily because the quests are both campaign quests, one after the other in Act 1: A Cold and Iron Faith. The Cost of Knowledge outlines Neyrelle and her mother’s reunion. Though, it doesn’t exactly go the way anyone would expect.
Head farther into the dungeon from where you left off in Storming the Gates. Your primary objective is to search for Vhenard and Lilith with Neyrelle. Keep following the path until you enter the highlighted area of the map. You should pass a Healing Well with a corpse nearby to inspect next to it. The corpse appears to be a dead priest with a massive gash across his neck that drained his blood.
Further into the highlighted area, you will find a person lying on the ground. Upon further inspection, you will learn that this person is Vhenard, Neyrelle’s mother. Though, Lilith is nowhere in sight. At this point, you should speak with Neyrelle to progress in the quest and begin a new cutscene in The Cost of Knowledge.
During the cutscene, you will learn that Lilith used Vhenard to help open the bridge for her and left her behind when she wasn’t about to pass over. Though, since Neyrelle wishes to end Lilith’s mission, Vhenard becomes upset and is disappointed in her daughter for not following in her path. At this point, against Neyrelle’s intentions, Vhenard begins to fight with Neyrelle. This fight starts in the next portion of The Cost of Knowledge.
Now, you must slay Vhenard’s demonic servants. Throughout the entirety of the boss fight, you will not do any direct damage to Neyrelle’s mother. Instead, she will continue to spawn demonic servants. Any time she does this, the damage done to the servants will also automatically damage Vhenard. You will take her down without dealing even 1 point of damage to Vhenard.
Once you’ve defeated Vhenard, you must speak to Neyrelle once more. She lets you know that she’s not upset. You were protecting her, and for that, you have done well. This completes The Cost of Knowledge in Diablo 4.