Subject to Testing

Tyranids

Sneakin' into your back passages and jumping your homies!

Genestealers. The most important thing I've found with this deck is playing the mind games: your opponent KNOWS all your units can Ambush and that you've got loads of resources, but are you waiting for the battle to begin at the infested planet or do you simply have a hand full of nothing? Can they take that chance? While they worry, play aggressively and set up some Raveners with an Acid Maw. Many things will die. Also, before people ask: I know that the Blazing Zoanthrope seems like a more sensible option for an Infest-based deck but I prefer the extra command the Lictor gives (plus they're a bit sneakier fluff-wise).