The eighth house is a post-ascension, succedent, and its Hellenistic name is the Idle Place, argos topos. Counting by whole signs it stands at no aspect to the rising sign, so it is in aversion to the Horoskopos, and the name records the consequence: a place that cannot see the ascendant is a place from which nothing is readily conveyed to the native.
It is one of the four averse places, with the second, sixth and twelfth. Of those four it is the only one that is succedent rather than cadent or, in the second's case, also succedent, so the eighth and the second are a matched pair: the two succedent houses in aversion, sitting opposite each other across the chart, one named for the gate of Hades and the other for idleness.
Its cusp is contested like every intermediate cusp. Whole-sign takes the eighth sign; Equal measures 210 degrees from the ascendant; the quadrant systems divide the arc from the descendant up to the Midheaven into three by their own rules.
There is a specific reason to care about this cusp more than most. The Lot of Death in this atlas is built from the eighth house cusp rather than from the ascendant, which makes it the one lot in that table whose value depends on the house system chosen as well as on the birth time. Two astrologers with the same data and different software will compute different lots, and neither will have erred.