Soulmill
Enchantment

Pay 1 life: Target player puts the top card of his or her library into his or her graveyard.
I was thinking about the various kinds of resource exchange in the game - in particular, what resources you can exchange life for directly without breaking the game. This particular relationship hasn't really been explored (no, I don't care about Wand of Denial), and I think it's worth a look.
I really like the card's flexibility - you can stick it in Ichorid or Reanimator and combo out, or you can use it aggressively to mill your opponent. There are even circumstances where you can use both.
The life/cards ratio could possibly use a little tweaking, but if it were any weaker this would basically just be worse than Glimpse the Unthinkable, which hasn't seen much play anywhere.