Pro Tour Journey into Nyx is shaping up to be quite the rumor season event. In addition to the matches played by competitive Magic's best and brightest, we're also getting to see the announcement for this year's fall large set tomorrow and, today, we got a streaming preview draft of the upcoming supplemental product full of mystery and backstabbing, Conspiracy.
And it turns out that Conspiracy's not just a set name - everybody's got their own plots in this format, so there's an entire card type purely used in Conspiracy draft, aptly named conspiracy itself. These are apparently free cards on a new kind of card face made to resemble a scroll with a wax seal, and they appear in Conspiracy booster packs at an unknown frequency (possibly exactly one in each). The rules are still not one hundred percent clear about them, but it seems as though you get to start with one of these in your command zone at the beginning of every game.
There are two kinds of conspiracies - one that begins face up and immediately provides a universally useful, but minor, bonus, and the other that starts face down (having the hidden agenda keyword) and that grants more powerful bonuses, but only to a specific card you had to name beforehand.
For example, the face-up conspiracy Sentinel Dispatch allows you to start the game with a 1/1 Construct artifact creature token with defender on the battlefield. This may block and kill the first creature an opponent might play, or serve as an early deterrent, which is a good way to get a quick advantage but isn't exactly gamebreaking. The face-down Double Stroke, however, copies any instant or sorcery of a specific name you play. This is obviously very powerful, especially when combined with an expensive spell that has a huge effect, but since it only works with the one you named, it might spend the entire game being useless if you never draw your named card.