Marrow-Gnawer in Ratopolis (EDH / Commander)

First of all, sorry my lack of english, but here is a little description about my Marrow Gnawer deck.
All advices are well received.
-Ramp for reducing not only the cost of Marrow, but also of his entire colony.
-Draw and tutor cards for getting one of the win conditions as fast as possible (including a combo for the ones who like them).

• Non rat-colony creatures for MORE fun, and also if you need a response in some difficult moments, for example:
  1) playing Skullsnatcher -i call him bojuka rat (_)- against a Meren's deck and his annoying frog;
  2) stealing opponent's biggest creatures (like Ulamog or Blightsteel Colossus) using the Piper ability and loosing only a few rats in the process.
  3) getting a Sheoldred resting in an opponent's graveyard with Ink-Eyes.
• Non basic land cards (nykthos, cabal) for casting Mawer again if he gets killed cause the protective spells failed (eldrazi monument, boots, greaves).
• A few artifacts for having a ridiculous amount of rats in early game.
• Finally "no mercy" can protect you and also allow you not to waste rats unnecessarily when using them as blockers.