Have yet to try this deck with pack rats. This addition can recycle fuck draws into new rats, increasing its numbers and therefore its power/toughness. The mutavaults can also pump pack rats and take adavantage of merfolk decks. These rats can also relieve a lot of pressure from bridge, since we can amass an army before the bridge gets destroyed, giving us a few more turns to block or an aggro plan B.

Still looking for a decent removal spell.
Between waste not, pack rat and bitterblossom, I'd prefer pack rat and bitterblossom as alternate wincon. since waste not is pretty bad for a mid game top deck.