I have a friend who has a Black Rat deck and he runs Doors of Destiny instead of Coat of Arms.
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Your deck looks good, I would suggest swapping out doom blade for terminate. I have found that Gluttonous slime is really good in case someone goes to get rid of your tokens, since gluttonous slime has flash. I run Hissing Iguanar he does damage when ever a creature goes to the graveyard, a good double whammy especially with Voracious dragon. I have a deck called Corpsepyre if you want to take a look. any ideas there would be appreciated.