Not sure what your budget is, but other handy lands include Reflecting Pool, Field of the Dead (if you can swap out some lands for snow lands), Mana Confluence, Temple of the False God, the Fetches on-color (or even Prismatic Vista or Fabled Passage if you're basic-heavy)
This means that, if you draw a decent hand, you can often deal a few decisive blows before your opponent has got their Mewtwo ex or Celebi ex online
Chittering Witch has some great art, though the name makes me think more of spiders (Witch's Web, anyone?) and insects than rats
Each shard is missing two colors, so it's focused on a specific color and its two allies
One of the best decks Ive had so far has been a straightforward Temur deck centered around blue and red
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