While you control it, cards that are "decorated" (which the card uses to refer to cards with "premium" foil, alternate art or frames, and promo cards) have a miracle cost of one snow mana (which means that you can play the card for one snow mana if it's the first card you drew that turn)
While its symmetrical effect is typically seen as a downside compared to Doubling Season, you should instead use its presence on the field to your political advantage: Dont remove me from the game, youre getting value off of my Primal Vigor, Wait, I can cast Primal Vigor next turn and we can swing in with all those Tempt with Vengeance tokens, etc
They carry the SR designation and represent the strongest, most competitive-demand cards in any given set
Expansions You can always check out how much of a certain set youve accumulated by selecting that specific set
Chances are, if there's 20 1/1 Goblins on the board, and 10 other big scary creatures, you'll only be leaving a puny gobbo on the battlefield