You get instant speed with the classic artifact and enchantment removal Green has to offer: Return to Nature, Natures Claim, Wilt or Krosan Grip (if you really, really want something destroyed)
Yawgmoth's Vile OfferingYawgmoth's Vile Offering has less applicability, but it can still find its way into many decks
I squeezed in a draft of my cube with the temporary setup and came up with a pretty compelling GW deck following the themes be3ing explored here
Welcome to a deck profile for a deck I call FIREWALL DECK
Plus, there are many different engines you can set up with Grixis cards, with different gameplay options, and thats one thing I appreciate from a color combination
Fringe : Branch of Vitu-Ghazi - I like the idea for some decks to play extra lands because they need like 28+ lands