Burton is well-known in the Magic: The Gathering (MTG) community, and sometimes sells oddities from the collection of a former WotC employee
Back way when, Wizards didn't really make sure that there were ENOUGH playable limited cards in the common slots for sets (no one was playing much limited before the inception of the Pro Tour, around the release of Ice Age ), so horribly unplayable cards like Snowfall and Balduvian Shaman glutted the common slots of packs - and commons are where most of the meat of your limited cardpool comes from
When done right and with luck, it should place you in a really strong position in comparison to all other players, and it will make you the table's target
While Im personally the most excited about Llanowar Wastes, since its basically the card Ive wished for ever since Theros came out, the other pain lands open up a bunch of new possibilities as well
This is a unique ability to have in Commander (especially in the command zone), and becomes deadly if paired with Eldrazi Displacer and Teleportation Circle
Some are more complex than others, which can make them not quite as favorable for people who are just starting out