Talisman of the Lich King (Patreon)

"Now This last one is interesting as it's only two pieces of the whole thing. Despite my efforts  I haven't found the rest and honestly I've stopped looking. But supposedly it grants the user access to a long gone liches dungeon, supposedly filled with arcana that hasn't been seen for 1000s of years."

DM notes - find all the pieces, go somewhere cool or get something cool. Easy device to make a long term quest with.