What's up with the flavor text, is Nahiri the bad guy again? What's she done now?
It was revealed that pre-Eldrazi, the kor had a global empire ruled from their skyclaves, flying fortress cities that had been destroyed over time including by the Roil. Nahiri is from this time, and she wants to end the Roil to make Zendikar great again. Post-Eldrazi, the skyclaves have floated back up into the sky, and Nahiri wants to find an artifact that can end the Roil permanently. Unfortunately, this power seems to kill and/or petrify organic life.