Greyish Rendering

The grey render bonds with the most intelligent member of a party (wizard probably) and will follow them to the ends of the multiverse while constantly getting in the way and causing chaos. It may even decide to create more grey renders to tag along for the next most intelligent party member.
Introduction ideas 

farmers concerned with something tearing up farmland, investigate and track it to its homeland

sold off by a disgruntled group of mercenaries who found it deep in a cave

Page 211 mords tome of foes, lvl 12 so late game