The Set Norns were an early C3 genetic breed created by Nightrunner. They were precursors of the Osiris Norns, the first "expressive" norn genome, which even predated Creatures Labs' own expressive genome. In appearance they were a cross of norn, ettin and grendel. They were capable ettin and grendel hunters, but were also equally aggressive against other norns. However to keep your gean pool unsetlike they could not breed and where fastagers so you would not want to breed them. They were once available from the Osiris Project website, now long defunct. The Set Norns are listed in the Museum of Lost Breeds at Creatures Unlimited.
The Set Norns have been found! KnyteTrypper, while searching through the norn adoption agency, came upon the last Set Norn. He has recreated the genome and has only changed the aging to be a bit slower, and left everything else intact. The Set Norn egg agent and starter norn pack are now available from his website, KnyteTrypper's C3/DS Nexus.