On top of the Stolen, why not hiring 1 Obedient Wretch (4ss) instead of the 2 rats (4ss too) ? If you don't have the Crows in hand, then Inevitable Fate the Obedient Wretch to make the 2 rats. In the worst case this is one more activation (for the same cost), and in the best case (if you have 2 Crows) this is 2 more rats almost for free (2 cards).
Note: The only issue is that you don't have anymore any Obedient Wretch (Rare 1).
Can we really do it twice (discard 2 cards to move 2 pits) ?
Crawling Plague: At the end of the turn, you may discard a card to move a friendly Plague Swarm Marker up to 6" in any direction.