Matthew understood.
Voldemort was very cunning. After discovering that the Peter Sirius had been impersonating was a traitor, he endured without revealing anything.
Voldemort had carefully prepared a trap for Dumbledore, causing him to be afflicted by a curse.
Matthew tried to use the Invisible Hand to pull the ring from Dumbledore's hand, only to find that it seemed welded in place, impossible to remove.
Dumbledore said painfully, "I tried... it was useless... this was a trap Voldemort... carefully prepared for me..."
Matthew took out a vial of golden liquid from his pocket. It was spring water collected from the Fairy Fountain, which could dispel curses.
When he poured the golden liquid over the ring, it was like cold water dripping into hot oil. It sizzled as waves of black smoke drifted into the air.
A moment later, the ring split into several pieces and fell from Dumbledore's finger.
Matthew poured the remaining liquid over Dumbledore's hand, and the blackened marks on his palm quickly faded.
The curse had affected too large an area. One vial of spring water was not enough, and Matthew had to use several before fully dispelling the curse on Dumbledore.
"Matthew... I thought I didn't have much time left..." Dumbledore's complexion had improved somewhat. Seeing Matthew take out another vial of spring water, he said, "This potion must be very precious. The curse has already been removed, so don't waste it."
Dumbledore knew this was a curse Voldemort had carefully prepared for him. Ordinary potions would likely have been unable to deal with it. Just now, he had truly thought his life was nearing its end.
Matthew was not particularly distressed over the Fairy Fountain water he had used. He had stored plenty of it, and the Fairy Fountain's effects would dissipate over time anyway.