Typically they do nothing at all most of the time, what you want from a card is one that has great odds of winning the game but that also does something significant when it doesn't win the game
Just like everyone else, I thought the ability would be some kind of drawback when I first read the card, but no, its just a creature that synergizes perfectly with what Golgari and Dimir are trying to do in the set
If you're playing a deck that floods the board with creatures, then you can simply make sure everyone else loses their creature and you get to keep yours
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You can get boxes of each of the following pack types, and pay attention to how many packs come in each box since it changes as WotC sees fit
Distant Memories lets you make only one of the two piles, but the other is randomthe card would be a lot more interesting if both piles were face down and your opponent had to guess whether the card you tutored was better than a Concentrate