Villager's Plague

If you get this in your starting hand, start the game with it on the battlefield. If a creature enters the battlefield under your control, put X -1/-1 counters on it, where X it's toughness -1. When it attacks, put a -1/-1 counter from it onto the blocking creature. If a creature an opponent controls dies from this ability, they lose life and mill cards equal to the creature's toughness, then you gain that much life. If at least 4 creatures died from this, transform this.