Back to Act II – Uma’s Curse
Go up and talk to Yennefer to find out she’s having trouble with the Megascope. She thinks there must be a magical disturbance nearby and asks you to investigate. She gives you a Potestaquisitor which will hum when you get near to the source of the interference.
Head down to the main room and get close to Uma. The device will hum but Uma isn’t the problem. Check a crate to the left of him to find Dimitrium Bombs. Vesemir will take them away while Geralt keeps an eye on Uma.
Head back up to Yen and she’ll have the Megascope working. You’ll have a brief conversation with Ida Emean aep Sivney, an Elven Sorceress, about Uma’s Curse and the White Frost. After the conversation the quest completes.