Also, discarding or milling a card that would be a permanent while on the battlefield does not trigger the Patron's ability.  A permanent only exists on the battlefield.  Anywhere else, they are called permanent cards or permanent spells (if on the stack).  Once a permanent spell resolves, it enters the battlefield and becomes a permanent.  Permanent spells are artifact spells, enchantment spells, creature spells, and planeswalker spells.


This is just one of those issue where you have to pay close attention to specific wording.  Once you've been playing a while, you'll notice these nuances and see them more easily.

I do like discard as a major theme of a deck, but I feel you need to focus a little more on blanket discard or discard that can be used multiple times.  Thoughtseize is an amazing card in a duel, but when you have three opponents, it becomes really weak.  Of course, it's okay to have one or two Thoughtseize-type cards, because you may be in a duel at some point, but I feel that you have more targeted discard than you need.  A definite addition to this deck would be Siphon Mind.  

Painter's Servant is banned, so Grindstone is useless.


Also, if you really want to do the mill strategy, you really should focus more on it.  Having more than one opponent makes it extremely difficult to win by mill, so there's no point to even having mill-based cards unless you're "all in".  Besides for mill, you really need to play blue as well, since it has the best mill cards.  Check out my UB Mill deck called Million to see what I'm talking about.  

Commander is Patron of the Nezumi, so it is discard focused to maximize the commander. Rats also synergize with the strategy and offer a secondary method to deal with opponents.

I'm confused.  Are you playing mill or rats ?