Sakari did not know where this light suddenly emerged from; however, she knew that it definitely had something to do with that wretched trephasia—and she was correct.
While Luna went around the room healing the captives, at the same time, she was also setting up the Grand Illumination Talismans she received from Maeva before the event started. After all, she was aware of the skounae's fragility to light. But that was not all. The Grand Illumination Talisman was not the type of talisman that could be activated on a timer; therefore, Luna decided to create her own 'timer' by using a Talisman of Obstruction.
A Talisman of Obstruction was used defensively as it forcibly delayed a talisman's activation by up to twenty minutes, depending on the talisman's strength and flawless timing by the user. Of course, since Luna was applying it to her own talismans, the latter part was of no concern.