Its as early as this. While we still didn’t get a hang of Avacyn Restored, rumors of the next core set are already appearing in the interwebs. First up is a camera pic of one of the set’s Intro pack which previewed a legendary black Dragon, and an image of Liliana in the booster pack.

The text in the card is believed to be:

Nefarox, Overlord of Grixis
4BB
Legendary Creature – Demon
Rare
Flying
Exalted
Whenever Nefarox, Overlord of Grixis attacks alone, defending player sacrifices a creature.
5/5

The source also said that the new intro pack includes an additional booster pack for a total of two boosters. Here is the scanned camera picture:

Magic 2013 is scheduled to be released this July.