Lets take a look at what Dimir has to offer, and then take a look at unguilded black Gatecrash cards
Farseek: Needed by Green to help other colors in the deck
Black Round Corner Foil Star Filler Card The next to make the cut is a card that if were being overly literal shouldnt have made the cut at all
Plot only as a sorcery.) Creature - Human Druid Draw (CTRL to add secondary) Evasion Garruk's Uprising When this enchantment enters, if you control a creature with power 4 or greater, draw a card
I see it has foretell, so you can get it for 3 but why does it have to cost so much in the same set as a better card that costs only G
If your Commander has Choose a Background, you may choose any one Background card that will essentially function as a second Commander, adding its color identity to your deck, and following the rules of Commander tax and going back to the command zone when it would move from the battlefield to anywhere else