From the official WotC site, we’ve been spoiled the art for the packs and sample packs – both of which are sporting Nissa Revane!
While there had been some rumors of Nissa being in the set, this essentially confirms that she’ll be in the set in some incarnation, even if it isn’t her elf-centered Nissa Revane printing from Zendikar.
In addition, Mark Rosewater confirmed that there will be 6 planeswalkers – 1 of each color, and one additional one of some sort: most likely a set Garruk to go along with Garruk the Slayer from the prerelease challenge.
Until next time,
EDIT: Less than an hour after writing this, Ajani the Steadfast was spoiled!