As described in "Magick of the Ancient Gods" by Michael W. Ford, the pouring of libations into the earth in offering to the ancient god or spirit invoked is a symbol and spiritual act of respect/honor and essentially feeding the deific mask/god you are calling. 

Pentagram Offering and Scrying Bowl  is sculpted of silver-plated brass, this piece is an elegant solution to those looking for a new take on the traditional offering plate or scrying bowl. Created in a design akin to a chalice, it features a wide base that narrows to a slender neck before expanding to form the basin. Its sides smooth and unadorned except for the pattern decorating the edge of its base, it flares out to a wide mouth with an open base decorated in a five pointed pentagram; a timeless symbol for the four elements united by divinity, or spirit.Standing approximately 2.75 inch high and measuring 3.75 inch wide, it is a squat piece that will not tip easily to spill its contents, and will readily contain all but the largest of your offerings. It could also easily be filled with a liquid of your choosing to gaze into for your scrying and divination.