Plague Rats

Ya, already have the cards, ordered the Hatchery the other day, should make the deck more consistent.

I gotcha.

I see a little bit of anti-synergy going on here. This deck desperately wants to have three lands to cast its rats, and desperately wants to build up rats (as on their own they're just three-drop 2/2's), but you're running lots of spells that make both those goals harder.

Up front, rats are only good when they swarm. One rat is just a 2/2, two rats are just two 3/3's, three rats are just three 4/4's. You can get the same thing by running green fatties that are 4/4's all the time. Plus, you're only running thirteen rats, so your chances of fielding more than two at a time are actually pretty slim. On top of that, you've got land/removal problems.

Innocent Blood and Smallpox lose you a creature. Smallpox loses you a land. You'd theoretically play both before you cast a rat, which is good synergy, but once you've got a rat/rats, topdecking one is a problem, so if you don't have one off the bat, you're running seven cards in the maindeck that you don't want to draw once you field a rat, which is the entire plan this deck wants. So, at that point, you've probably got enough lands, so you've got seventeen-ish lands and seven removal you don't want to topdeck, so you've got almost exactly a 50/50 chance of drawing a card every turn you don't want.

On top of that, when you do play Smallpox turn 2, you lose a land and thus can't drop a rat the next turn, so you're slowing yourself down and letting opponent have a chance to catch back up. Smallpox is a really cool card and combos perfectly with Hatchery, but you've sort of got to build the whole deck around it to make it work and I don't think that's going to happen very consistently. Typically, Smallpox pairs with stuff like Life from the Loam, Wasteland, Urza's Saga, a bunch of cheap cheat artifacts, and a high land count so you take advantage of denying opponent resources while eeking out the win slowly in the grind.

This build is sort of trying for both without committing to either, which makes neither work very well. A turn 1 rat in exchange for a Dark Ritual goes -1 against any spot removal, makes your Smallpoxes and Innocent Blood's a bad investment, and only swings for 2 damage until turn 3, at which point you get a 3/3. You also can't rely on Swarmyard to cheese your way around this, as sacrificing isn't destroying, so you can't regenerate them.

So, in general I'd sort of advise picking which theme you want to run and focusing on that more. You could build a rat swarm deck on the cheap, especially with how strong cards like Karumonix, the Rat King.

Just some thoughts, not trying to diss the build.

I've played Karumonix in a rat build for Standard, and he is such a value-train of a card.

Nothing says good value like a lord card that's got a body of its own that nets you card advantage