Purely rat related scrolls would be:
Junkyard
Beast Rat
Rat King
Mangy Rat
Pestis
There are some nice synergies and I suppose you can build a deck around that. I think would need to play this aggressive buffing you creatures and debuffing the enemy. Grwoth offers nice scrolls to make beasts bigger. I would probably throw some Vaettrs and wolves in there, too. But unfortunately I'm experienced enough to create a working list out of the blue.
I would like to see a deck like that, though.
Edit:
After a bit of theory-crafting I came up with this:
http://scrolldier.com/deck/3467idk if that would work well, but maybe it's a start
