I wonder if it might be Impresario. He's unnamed, and I'm fairly sure his house is full of ancient treasures, one of which might be the old school myth. Also that deal in WoR with him could be the rift. It's all I've got, sorry

The old school myth line is a good one though. I thought Lone Wolf first too, especially because he appears in V as well (not exactly old school in comparison to VI, but still!).