Quick answer: Eye of Insight drops once you clear the puppets in the masked arena. It upgrades the One-eyed Bow.
Where to get Eye of Insight
Start at the Covered Corridor bell and stay alongside the pond for roughly 190 m to reach Willow Pavilion. Go through a shrine chamber and an arena beneath hanging masks, then open the red double door and enter Leng Tu’s Study.
At the far end of the veranda, beside a pillar, a stair drops into a round arena under hanging opera masks and red ropes. Seated dolls ring a glowing red-orange pillar with a white figure inside. Stepping in triggers a scene in which “Yu’er’s body controlled by the Herald” says: “You’ve walked through mountains of corpses to get here… how are you and I any different?” When the line finishes, two Alloy Cannon Puppets, two Spear-Shield Puppets and a big-headed doll spawn, and cannon shells and a purple blast hit at the same moment.
In our run, standing still when the line ended was fatal within seconds, so start moving immediately. Eye of Insight drops once you clear the puppets in the masked arena.
The Mirage Estate collectibles page covers the rest of the region.
Eye of Insight item card
The item card reads:
A protective talisman left by her father, in hopes that she would leave this world of blades behind and venture into the vast lands beyond the Wulin, without shouldering his bow or retreading his path.
Yet deep in the Discordance, the thing that had watched her father followed the blood down to her, and turned its gaze on her too. The talisman was tainted with it. Still, she could feel her father’s protection lingering within it.
Its effect line reads: “Used to Soul Temper the One-Eyed Bow.”
What Eye of Insight does
Hold Phantom Edges to draw and charge your bow. Charge up to 3 stages, each adding an additional arrow. Consumes 1 Remnant Spark
Soul Tempering the One-eyed Bow: Cost and steps
The upgrade costs 5,000 Remnant Dust plus Eye of Insight. Myst handles the work at the Order’s underground tavern in Pangzhen. The general process is covered in how to Soul Temper.
After that, the bow has Rapid Shot. Hold Phantom Edges to draw the bow and charge the shot. Each Rapid Shot uses one Remnant Spark. The rest of the game’s upgrade materials are listed in all Soul Tempering materials.
