Final answer:
The name of the vessel used for sacrifices after the Pompe reaches Eleusis is called Plemochoai, which played a significant role in the concluding libations of the Eleusinian Mysteries.
Step-by-step explanation:
The multi-faceted sacrifice that occurred after the Pompe reaches Eleusis involved the use of a vessel called Plemochoai. This was not just a vessel, but also marked the conclusion of the Mysteries with a libation, one Plemochoai upturned to the west and another to the east. Such ceremonies were rich in symbolism and signified the offerings and the honor bestowed upon the deities during these sacred rites.
The Plemochoai, used for the concluding libations, were part of the Eleusinian Mysteries, a series of rituals with deep religious significance, which included sacrifices, processions, and sacred dances accompanied by music. The entire process was one of solemnity and celebration, reflecting the spiritual beliefs and practices of the society at the time.