From Edge of Darkness Wiki
Circle of the Crone Sourcebook p. 40
Having an altar present in one’s haven and possessing the Altar Merit are not necessarily the same thing. An Acolyte can have an altar with various reagents, personal effects and idols, but that altar does not grant her any kind of mechanical bonuses. It is a vehicle for her faith, to be sure, and the vampire surely believes that the altar is necessary to fuel her belief and her powers. The altar offers no bonuses to rolls, however.
An Acolyte can possess an altar that helps her perform Crúac rituals specifically. This altar likely contains instruments that allow her to spill her blood, as well as a place to spill the blood and even dispose of it — a bronze sink or well may grant her a place to empty her Vitae, as could a series of ritual cruets to contain the spilled blood.
The points taken in this Merit grant the vampire one or two bonus dice to all Crúac activation rolls made using the altar. The number of bonus dice is equal to the Merit’s rating (• or ••). Note that some Crúac rituals (such as Cheval) require the target of the sorcery to be in sight. If the target cannot be dragged before the altar, the Merit points do not grant any bonus at all. A ritual such as The Hydras Vitae, on theother hand, is ideal for casting at an altar.