Circle of Cerberus
Description: The necromancer bathes, fasts and abstains from all physical comforts and pleasures, most especially sensual ones, for a night. Then she dons well-maintained, high-quality robes or other clothing. She draws a circle on the floor in a place of safety. She may then proceed to use other necromantic powers, confident that her protection against ghosts and spirits has been enhanced.
System: The player rolls Intelligence + Rituals at a difficulty of four (4). Each success subtracts two (2) from the difficulty of all rolls the player must make to resist any attempted harm or influence on the part of a ghost, specter or spirit, so long as the necromancer remains inside the circle. Treat any botches scored while attempting to use necromantic rituals and paths as failures instead. The ritual itself takes less than five minutes, while the period of purification needed to qualify for this ritual is an entire night. This ritual's effects last as long as the caster remains inside the circle. No special ingredients are required beyond the caster's purity and a suit of high quality clothing.
Notes: This description isn't verbatim, but rather a close approximation of the ritual as described in Blood Magic - Secrets of Thaumaturgy. It was determined early on in the 'Game' that this ritual was vastly over-powered, as is common with all written descriptions of Giovanni rituals. In an attempt to keep the essence of the ritual without it being over-powered, Bruce created a variant called 'Ceremonial Circle' which can be found in his 'Grimoire'.
Reference: Blood Magic: Secrets of Thaumaturgy - Page 105.