These cards, while considered promos, have been left off the list due to their wildly varied pricing and ridiculously high value
Ridiculously, this is the top of the list because it has more of a chance of seeing Modern play than most of the Assassin's Creed cards
For 4 mana you dig seven and can drop two lands of any type from your library to the battlefield tapped
BPhillipYork: This can be broken, there's way to create mana enough to blink this, Dockside Extortionist is an obvious huge mana generator here, but there's also Su-Chi and other sources, you could also do something like sacrificing Gnawing Vermin or Stitchers Supplier and generate a lot of mill, if you were into that sort of thing
Badgermole Cub also allows your animated lands to add an additional when they're tapped for mana, providing solid ramp for earthbending and land animation decks
It is expected that the value will continue to rise as long as the demand for vintage MTG items remains strong