Jed MacKay 
Magic #12 [PDF ebook] 

A newly-debuted Planeswalker must reach Ravnica to seek Kaya the ghost assassin’s help with a vengeful specter, while Chandra seeks ancient machines that could breach the unseen barrier around Ravnica, and Garruk’s tireless pursuit of the sadistic and elusive Tibalt may be Chandra’s best lead. Meanwhile, our new trio of Planeswalkers join together as their goals align, speeding off to pick up the trail in Emeria, the shifting Sky Ruin in Zendikar!But should they succeed in reaching Ravnica, they’ll face the master dominating Tibalt and Davriel, perhaps the greatest mage the plane has ever known