Quelques révélations intéressantes de Mark Rosewater:

And then to, Innistrad. Clearly it was the centerpiece of the panel. Mark Rosewater declared that the theme of the set is themed 'Classic Horror'. He went on to say there are tribal and graveyard mechanics in the set, and mentioned a few of the tribes in the set. Vampires will be in the set, of course, making an impression in Black and Red and returning to them after their surge in Zendikar and their absence from Mirrodin. Zombies will be expanding out of Black into Blue. Werewolves will be rearing their heads in Green and Red after being solely restricted to Black in the past. Other unnamed tribes will be in the block, ones that fit the 'classic horror' tropes that MaRo mentioned. One such unnamed tribe is that of 'Spirit' which was revealed in the handful of cards spoiled from Innistrad in Duels 2012.
A new Liliana Vess was confirmed to be in the set, alongside another unnamed 'familiar' planeswalker. One likely guess is that of Zendikar's Sorin in a new form, but I am not convinced that this would make sense given that that would make Black quite powerful in limited as it might play host to the two Planeswalkers in the set. The other two top guesses would be the Duels 2012 planeswalkers: Kiora Atua and Ral Zarek. Who will it be? Only Wizards knows.

Pour résumer en français, le bloc s'inspire des thèmes d'horreur classique, les vampires feront leur retour en noir et rouge, les zombies seront pour leur part en noir et bleu et enfin, les loups-garous seront eux en vert et rouge (au lieu d'être simplement noir comme à l'époque.).
Innistrad devrait également revoir un système de tribu un peu à la manière de Lorwyn, et il y aurait d'autres tribus que les trois sus-citées. Notamment les esprits qui auraient été spoilé dans le jeu Duels of the planeswalkers 2012.

Enfin, dans le bloc de base, il y aurait deux autres arpenteurs en plus de Liliana qui est donc confirmée! Les rumeurs parlent de Kiora Atua et Ral Zarek, les deux arpenteurs de Duels of the planeswalkers 2012. Marc Rosewater parlait d'un arpenteur familier, mais l'illustration de Sorin visible plus bas laisse dubitatif: deux arpenteurs noirs dans le même set?

Une petite illustration: