Originally printed in Ravnica, and again in Tenth Edition, the Scion grows in power and toughness with each creature you control. It's a fun card that could be a bomb in draft, but otherwise it's pretty much always been a bulk rare. Now it's at common. From a draft perspective, this is pretty neat, but more importantly, it makes it accessible to Pauper players. The all-common Pauper format is always happy to see former uncommons drop to common, but for a rare to drop down to common is especially unusual.
As green beatdown decks are fairly common in Pauper, it's a bit of a surprise that Scion of the Wild hasn't really seen play in the format. There is a Green/White Token list I found that runs two copies, but beyond that, it only sees some limited play in Rhys the Redeemed and Trostani, Selesnya's Voice Commander decks. It could be a good choice for a Pauper Commander token deck, however.