Pack Rat is by far the strongest card.i would stick with the rat theme.

heard of Relentless Rats? ;)

also if you can afford them a playset of AEther Vial would be an insane upgrade.

I have been looking at Relentless Rats but don't know what to get rid of to accommodate them?

possible cards to get rid of:Crypt Ghast : not a rat and and the mana is not that important, consider Nykthos, Shrine to NyxGutter Skulk: just a 2/2 for 2.nezumi cut-throat: can still be in it because of te fearOgre Slumlord: a bit to slow but can still be in as 1-offOkiba-Gang Shinobi: is not a good card. when you can ninjutsu him in, a lot of players would already have an almost empty hand, if not empty.Patron of the Nezumi: way to slowWast Not: fun card but hard to get value of.Wring Flesh: if it's for removal, cards like Doomblade and Go for the Throat are way better options.

note that I type this from a competitive standpoint.but those are the cards I would consider taking out for Relentless Rats and aether vial. there is also a rat with unearth that says that every player discards a card. Rotting Rats he's also an option

In my opinion, the sideboard needs to be revisited entirely. Also, look at Stronghold Rats for an evasive threat, or Swarm of Rats for a big beater.

I'm also going to look up some utility cards with madness casting options on Gatherer for you. There's a good Reanimator option that can be cast for but I forget the name. I'll comment again with more suggestions and I'll look at that sideboard too.

I didn't mean to sound harsh about the sideboard, I just think it could be repurposed to help the deck in specific ways. :)

I love Rat tribal! +1 for joining the club.

JakeHarlow - yeah the sideboard was just a notepad really. Aether vial seems really useful but is pretty expensive from what I can see