A Crystal Skull is a specially prepared artifact often used by Thaumaturgists to contain raw power for eventual use later. In 1936, such a skull was acquired by Agostino Raffaelle Mikael Selletti, which was used to collect some power from the Crematorio Punta di Tristezza during an investigation.
Later, that same skull was used to disrupt a powerful ritual being performed by Red Court attempting to harness a massive amount of negative power which had accumulated at the All Saints Health Resort. BU removing the source of their power, the ritual failed, collapsing and then exploding in a ball of raw magical energy. This killed over two-dozen red court vampires, but destroyed the skull in the process.