I used to use Soldevi Digger all the time. It's one of my old favorites, but people always seemed to underestimate it. I suppose it's the whole "bottom of your library" thing. Unless you shuffle your library, for most decks, putting a card on the bottom means that you'll never see it again for the rest of the game. For some control decks and combo decks, it actually matters. While I'm not currently using Soldevi Digger in any decks, I'd do so if I found an appropriate situation. It's way cooler than Elixir of Immortality and such because you can choose to leave most of your graveyard where it is and only put the top card back into your library when it's a card you actually want.