70. Well

Navani conducts a series of experiments with Stormlight, Voidlight, and Lifelight to understand how different types of Light work and whether they can be combined to create Towerlight and restore the Sibling's powers. She also negotiates with the Sibling to locate one of the tower's nodes and plans to have Kaladin defend it, but learns the Fused have already discovered and seized the node in the Breakaway market well.

Navani begins with control experiments using tuning forks to transfer Stormlight between gemstones. She discovers that the three ancient pure tones of Roshar correspond to Honor, Odium, and Cultivation—information Raboniel possessed but Alethi scholars did not. Navani theorizes that Towerlight is created by combining Stormlight and Lifelight and attempts various experiments to mix these Lights using tuning forks and pressure differentials, but all fail. When Raboniel sends her a diamond of Lifelight, Navani tries again with this new material but exhausts it without success. Frustrated but methodical, Navani decides to create hidden fabrial weapons disguised as failed experiments to defend the crystal pillar if she makes a breakthrough. She contacts the Sibling through its vein in the wall, learning that Odium's tone has damaged the Sibling's connection to the other two pure tones and that Towerlight doesn't mix but rather emerges as a unified product from both parent Lights. When Navani suggests the Sibling might bond with a Parshendi Radiant from Bridge Four rather than humans, the Sibling considers it. In exchange for this possibility, Navani persuades the Sibling to reveal the location of one of the two remaining nodes: the well at the center of the Breakaway market on the first floor. The Sibling suggests Kaladin could reach it through the aquifers and infuse it with Stormlight to counteract the corruption. However, as Navani studies in the archive afterward, the Sibling's light flashes urgently—the Fused have already discovered and seized the node. Kaladin is too far away to reach it in time. Navani resolves to distract Raboniel while trying to warn Kaladin.