When I slew the Archdemon, the final boss of Origins, I jumped up on his head, and rode him (while stabbing him repeadetly with both my swords) until he fell to the ground, then (through some mysticism) I ran back, picked up a conveniently placed sword on the rooftop, and, in a brilliant flash of light, completely obliderated the Archdemon once and for all.
When I slew the Mother, the final boss of Awakening, I stabbed her in the face, twice.
Am I the only one who was slightly dissapointed by this?
Even the normal broodmothers in Kal' Hirol got a cooler death than this (they were blown up by some psychadelic lyrium cube).