Scaffold refers to the structure used for execution by hanging. It's a somewhat clumsy phrase meaning: the last attempt to drink someone's blood after they were executed (presumably hanged)
Thanks, I thought it might be something relating to execution but was confused by the Google results which was had a Wikipedia article stating "scaffolding, also called scaffold or staging, is a temporary structure used to support a work crew and materials to aid in the construction, maintenance and repair" as well as a lot of pictures of such structures.