This Mana Storm article features a new advancement called the Vale Bearer.
The Vale Bearer does almost nothing by itself, adding a guardian symbol to any card that wants one, but otherwise having no effect in combination with Fertile Soils or Cursed Lands. However, if you can get two other guardians onto the same card (ideally from the Sentry advancement in the expansion Vale of Magic, which costs 3 and provides both guardians on a single advancement or the level 3 Stag from the base game), then suddenly the big tortoise gets all three spirit symbols. Every time you play the resulting card, you’ll be able to get just about any level 1 vale and still have a symbol to spare. A very lucky player might be able to throw all three Vale Bearers on one blank card for the ultimate combo!
– Article by Will Pell