The object is to get Exquisite Blood and Sanguine Bond out quickly. To help find these, you can play Commune with the Gods, though it is recommended you do this only after having at least 5 lands on the field, so you don't manatap yourself accidentally (As you'll be discarding 4 of the 5 you draw).
If you do find you're having trouble obtaining lands, you can use Animist's Awakening to run through a portion of your library for more.
Creeping Mold helps with flexibility to remove things your opponent might throw down.
When you use Commune with the Gods, or simply by combat, you may find a good portion of your creatures are killed off.
Creeping Renaissance
goes off of your permanent's type, not their subtype. This means if you accidentally lose a ton of rats with Commune to the Gods, or you drew nothing but lands, you can get them back next turn. This also means that while the individual rats may not pass the bolt test, it does help negate the effectiveness of it.
Because there isn't anything in here to ward off flyers,
Plummet
was added to simply remove those from the game.
Retreat to Hagra
was chosen because it works well with Sanguine Bond. You'll gain +1 and your opponent will lose -2 when they work together. Likewise,
Retreat to Hagra
and Exquisite Blood yields +2 and -1. If you do not have Sanguine Bond or Exquisite Blood out, you can still benefit with a creature gaining Deathtouch. When your opponent attacks, simply block with your Deathtouched rat and remove that creature from the battlefield. The reason there are 3x (Edit: 4x for testing) of all Sanguine Bond, Exquisite Blood, and
Retreat to Hagra
is because if you are able to pull out all three (Which you'll find is actually easier than it might seem), it's automatically game over once your next land comes out, which again Animist's Awakening will help you do at a moment's notice.
Ravenous Rats
is a cheap and weak card to play, but forcing an opponent to discard is always nice. it also works as a good sacrifice for
Marrow-Gnawer
's ability. Once you activate this, just keep tapping and sacrificing a Token. They're weak, but your opponent will struggle to block all 10 at a time.
There aren't many
Locust Miser
's in the deck and I might fix that later. Honestly even just reducing your opponent's hand by 2 is good, but if I can work in three of them than your chances of reducing it by at least 4 is even better.
Lastly, Relentless Rats is obviously your frontline here. At so many in the deck and having 22 lands, you should be able to get one of these out by 4th round. From there the chances of pulling more only increases. In testing I've had moments where I put down two at a time.
Still fixing some of the balancing but for now this feels fine for what it is.