This is a mono-black rat deck with Graf Rats and Midnight Scavengers to meld into Chittering Host. I built this by request for someone on Fiverr with a budget of $15. If you want a deck built, you can find me on Fiverr as genoslugcs.

The Deck

Alright, first up, of course, we have Graf Rats and Midnight Scavengers to meld into Chittering Host. Beyond those, we have a package of disruptive rats, rat payoffs, and interaction to control the game until you have a chance to meld. The deck functions well and can win even without melding but I did get it several times during testing.

So, let's break down some of the other cards in the deck.

Rats And Rats Matter Cards

Even though Midnight Scavengers isn't a rat, Graf Rats is, and that's enough to run rats! There are a couple of big upsides and synergies for the tribe that work well for this strategy.

First up, and most importantly, is Karumonix, the Rat King. When it enters the battlefield, you'll look at the top five cards of your deck and get up to five rats! Considering 23 of our 28 creatures are rats, this is some massive card advantage that helps keep the threats coming. It can also find the rat half of the meld cards. 

It also has toxic 1 and gives all other rats toxic 1, too. If this stays in play, you've got a real threat of winning via poison counters. That said, the deck won by regular combat damage most often in testing. That's the beauty of toxic... The creatures still deal regular damage, too.

Still, just to make the infect threat more real (I mean, who doesn't want to deal 10 damage instead of 20?), we also play four Septic Rats. It's worth mentioning that toxic and infect stack. So, for example, if you have Karumonix, the Rat King in play with Septic Rats you'll get all the infect from Septic Rats plus the toxic one.

Then, to round out our rat package, we have full playsets of Burglar Rat, Lord Skitter's Butcher, and Thornplate Intimidator. All of these cards have some sort of utility - Burglar Rat comes down early, and strips cards from the opponent's hand, and Lord Skitter's Butcher has three strong options. These ETB triggers can be bought back in the late game with Midnight Scavengers too, which is nice.

And finally, we have Thornplate Intimidator, which also disrupts the opponent's gameplan via removal, forced discard, or at the very least, draining them for some life. And if you've got the extra three mana for offspring ability, you'll get a 1/1 token with the same ability.

The cherry on top of all these rats is a single copy of Ogre Slumlord. It's not a rat, but it makes rats and gives them all deathtouch. This means that even our Burglar Rat, from which we've already gotten ETB value, can block their biggest creature and trade. Deathtouch also works amazingly well with the menace ability option on Lord Skitter's Butcher. Now, if they want to block, they'll need two creatures, and they're both going to die!

Other Removal

Our creatures pack a fair amount of disruption, but we are mono-black, and we're going to play even more kill spells. We've got four Cast Down and three Long Goodbye. These are cheap to cast, instant speed, and should be able to handle almost anything you come across that actually makes it to the board and survives blocking.

At the top of the curve, we have two Corrupt, which could be used as removal in a pinch. However, they're mainly here to target the opponent and finish out games. Considering you also gain life, this will, at minimum, be a 12-point life swing when you cast it. I believe that you cannot run 23 swamps and not play Corrupt. You should have no problem getting to the late game, and we want a couple of heavy hitters when we do!

The Sideboard

All my decks come with a sideboard, and here is ours. I'll give a basic rundown of what each card is for.

• Meteor Golem - Mono-black can't deal with artifacts and enchantments well. So, this can come in to deal with things like Ensnaring Bridge that we couldn't win through.
• Check for Traps - This can come in vs. control or combo decks that don't have any/many creatures.
• Duress - This can come in vs. control or combo decks that don't have any/many creatures. Between this and Check for Traps, you have enough hand disruption to side out nearly all your hard removal, if need be.
• Ritual of Soot - This is a bit of a reset button against very low-to-the-ground aggressive decks or tokens.
• Tormod's Crypt - Comes in against anything looking to use their graveyard to their advantage.