Jed MacKay 
Magic #13 [PDF ebook] 

In Zendikar, tomb-raiding and death-defying adventures await as our three heroes finally learn to work as a team-with Chandra Nalaar as the unexpected and reluctant leader. In the hazards surrounding the Sky-Ruin, they encounter [REDACTED], pushing Garruk’s hatred to the limit and sending the three into a reckless pursuit in the dangerous ruins. Who is this mysterious figure that’s caught Garruk’s ire? And what new perils await in the depths of this ancient plane?