Some cards like Cabal Ritual were printed at different rarities in other sets (Cabal Ritual was printed at uncommon in the Magic Online set Vintage Masters )
Basicly rebacking is the process of tearing of the back of an reprint CE/IE card and glue it to an original magic back
Look at Force of Will with 318 pristine copies already
Its a complex balance of negotiation, trying to build for Casual tables, and its why so many players gravitate toward cEDH where their expectations can rarely be disappointed
He also has a Blood Artist effect: whenever another creature dies, you gain one life and target opponent loses one life
It looks like almost half of these inclusions come from Toph, the First MetalbenderToph, the First Metalbender decks (an area I dabbled in that was doing a lot more than earthbending), but to be honest, I still don't get it