I started with Blue/Green Investigate. I then moved to White/Green Investigate, and then I played against a great Blue/Green Investigate. From those three builds, I picked what I thought were the best cards, and this is what I came up with.
Graf Mole's life gain is incredibly useful. Here are two solitaire end-games. Lifegain decks cannot be piloted in Solitaire. I am showing these to give you an idea of how awesome the end-games can be with this deck. Against real decks, though, removal will trim these end-game states.
The "killer move" in this deck is to make a creature unblockable by tapping two artifacts with Whirler Rogue. I first lost against this trick, and then willfully stole it for my deck.