Villager Merchant

When Villager Merchant enters the battlefield,
exile the top three cards of your library until
Villager Merchant leaves the battlefield.
{t}, Discard a card: Put a card Villager Merchant
has exiled into your hand and you gain 1 life.
These long-nosed folk love to trade certain items for
giant green emeralds. Unfortunately, the only use for
these emeralds is, well, trading with villagers.